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69389

WednesdayDecember 16, 1998

Part IV

EnvironmentalProtection Agency40 CFR Parts 9, 141, and 142National Primary Drinking WaterRegulations: Disinfectants andDisinfection Byproducts; Final Rule

69390 Federal Register / Vol. 63, No. 241 / Wednesday, December 16, 1998 / Rules and Regulations

ENVIRONMENTAL PROTECTIONAGENCY

40 CFR Parts 9, 141, and 142

[WH–FRL–6199–8]

RIN 2040–AB82

National Primary Drinking WaterRegulations: Disinfectants andDisinfection Byproducts

AGENCY: Environmental ProtectionAgency (EPA).ACTION: Final rule.

SUMMARY: In this document, EPA isfinalizing maximum residualdisinfectant level goals (MRDLGs) forchlorine, chloramines, and chlorinedioxide; maximum contaminant levelgoals (MCLGs) for four trihalomethanes(chloroform, bromodichloromethane,dibromochloromethane, andbromoform), two haloacetic acids(dichloroacetic acid and trichloroaceticacid), bromate, and chlorite; andNational Primary Drinking WaterRegulations (NPDWRs) for threedisinfectants (chlorine, chloramines,and chlorine dioxide), two groups oforganic disinfection byproducts (totaltrihalomethanes (TTHMs)—a sum of thefour listed above, and haloacetic acids(HAA5)—a sum of the two listed aboveplus monochloroacetic acid and mono-and dibromoacetic acids), and twoinorganic disinfection byproducts(chlorite and bromate). The NPDWRsconsist of maximum residualdisinfectant levels (MRDLs) ormaximum contaminant levels (MCLs) ortreatment techniques for thesedisinfectants and their byproducts. TheNPDWRs also include monitoring,reporting, and public notificationrequirements for these compounds. This

document includes the best availabletechnologies (BATs) upon which theMRDLs and MCLs are based. The set ofregulations promulgated today is alsoknow as the Stage 1 DisinfectionByproducts Rule (DBPR). EPA believesthe implementation of the Stage 1 DBPRwill reduce the levels of disinfectantsand disinfection byproducts in drinkingwater supplies. The Agency believes therule will provide public healthprotection for an additional 20 millionhouseholds that were not previouslycovered by drinking water rules fordisinfection byproducts. In addition, therule will for the first time providepublic health protection from exposureto haloacetic acids, chlorite (a majorchlorine dioxide byproduct) andbromate (a major ozone byproduct).

The Stage 1 DBPR applies to publicwater systems that are community watersystems (CWSs) and nontransientnoncommunity water systems(NTNCWs) that treat their water with achemical disinfectant for either primaryor residual treatment. In addition,certain requirements for chlorinedioxide apply to transientnoncommunity water systems(TNCWSs).EFFECTIVE DATE: This regulation iseffective February 16, 1999. Compliancedates for specific components of the ruleare discussed in the SupplementaryInformation Section. The incorporationby reference of certain publicationslisted in today’s rule is approved by theDirector of the Federal Register as ofFebruary 16, 1999.ADDRESSES: Public comments, thecomment/response document,applicable Federal Register documents,other major supporting documents, anda copy of the index to the public docketfor this rulemaking are available for

review at EPA’s Drinking Water Docket:401 M Street, SW., Washington, DC20460 from 9 a.m. to 4 p.m., EasternStandard Time, Monday through Friday,excluding legal holidays. For access todocket materials, please call 202/260–3027 to schedule an appointment andobtain the room number.

FOR FURTHER INFORMATION CONTACT: Forgeneral information contact, the SafeDrinking Water Hotline, Telephone(800) 426–4791. The Safe DrinkingWater Hotline is open Monday throughFriday, excluding Federal holidays,from 9:00 am to 5:30 pm Eastern Time.For technical inquiries, contact TomGrubbs, Office of Ground Water andDrinking Water (MC 4607), U.S.Environmental Protection Agency, 401M Street SW, Washington, DC 20460;telephone (202) 260–7270. For Regionalcontacts see SUPPLEMENTARYINFORMATION.

SUPPLEMENTARY INFORMATION: Thisregulation is effective 60 days afterpublication of Federal Registerdocument for purposes of theAdministrative Procedures Act and theCongressional Review Act. Compliancedates for specific components of the ruleare discussed below. Solely for judicialreview purposes, this final rule ispromulgated as of 1 p.m. Eastern TimeDecember 30, 1998, as provided in 40CFR 23.7.

Regulated entities. Entities regulatedby the Stage 1 DBPR are community andnontransient noncommunity watersystems that add a disinfectant duringany part of the treatment processincluding a residual disinfectant. Inaddition, certain provisions apply totransient noncommunity systems thatuse chlorine dioxide. Regulatedcategories and entities include:

Category Examples of regulated entities

Industry ................... Community and nontransient noncommunity water systems that treat their water with a chemical disinfectant for either pri-mary of residual treatment. In addition, certain requirements for chlorine dioxide apply to transient noncommunity watersystems.

State, Local, Tribal,or Federal Gov-ernments.

Same as above.

This table is not intended to beexhaustive, but rather provides a guidefor readers regarding entities likely to beregulated by this action. This table liststhe types of entities that EPA is nowaware could potentially be regulated bythis action. Other types of entities notlisted in this table could also beregulated. To determine whether yourfacility is regulated by this action, youshould carefully examine the

applicability criteria in § 141.130 of thisrule. If you have questions regarding theapplicability of this action to aparticular entity, contact one of thepersons listed in the preceding FORFURTHER INFORMATION CONTACT sectionor the Regional contacts below.

Regional Contacts

I. Kevin Reilly, Water Supply Section,JFK Federal Bldg., Room 203, Boston,MA 02203, (617) 565–3616

II. Michael Lowy, Water Supply Section,290 Broadway 24th Floor, New York,NY 10007–1866, (212) 637–3830

III. Jason Gambatese, Drinking WaterSection (3WM41), 1650 Arch Street,Philadelphia, PA 19103–2029, (215)814–5759

69391Federal Register / Vol. 63, No. 241 / Wednesday, December 16, 1998 / Rules and Regulations

IV. David Parker, Water Supply Section,345 Courtland Street, Atlanta, GA30365, (404) 562–9460

V. Miguel Del Toral, Water SupplySection, 77 W. Jackson Blvd., Chicago,IL 60604, (312) 886–5253

VI. Blake L. Atkins, Drinking WaterSection, 1445 Ross Avenue, Dallas,TX 75202, (214) 665–2297

VII. Ralph Flournoy, Drinking Water/Ground Water Management Branch,726 Minnesota Ave., Kansas City, KS66101, (913) 551–7374

VIII. Bob Clement, Public Water SupplySection (8P2–W–MS), 999 18th Street,Suite 500, Denver, CO 80202–2466,(303) 312–6653

IX. Bruce Macler, Water Supply Section,75 Hawthorne Street, San Francisco,CA 94105, (415) 744–1884

X. Wendy Marshall, Drinking WaterUnit, 1200 Sixth Avenue (OW–136),Seattle, WA 98101, (206) 553–1890

Abbreviations Used in This Document

AWWA: American Water WorksAssociation

AWWSCo: American Water WorksService Company

BAT: Best available technologyBDCM: BromodichloromethaneCDC: Centers for Disease Control and

PreventionC.I.: Confidence IntervalsCMA: Chemicals Manufacturers

AssociationCPE: Comprehensive performance

evaluationCWS: Community water systemDBCM: DibromochloromethaneDBP: Disinfection byproductsD/DBP: Disinfectants and disinfection

byproductsDBPR: Disinfection Byproducts RuleDBPRAM: Disinfection byproducts

regulatory analysis modelDCA: Dichloroacetic acidDOC: Dissolved organic carbonDWSRF: Drinking Water State Revolving

FundEC: Enhanced coagulationEJ: Environmental justiceEPA: United States Environmental

Protection AgencyESWTR: Enhanced Surface Water

Treatment RuleFACA: Federal Advisory Committee ActGAC10: Granular activated carbon with

ten minute empty bed contact timeand 180 day reactivation frequency

GAC20: Granular activated carbon withtwenty minute empty bed contacttime and 180 day reactivationfrequency

GDP: Gross Domestic ProductGWR: Groundwater ruleHAA5: Haloacetic acids

(five)(chloroacetic acid, dichloroaceticacid, trichloroacetic acid, bromoaceticacid, and dibromoacetic acid)

HAN: HaloacetonitrilesICR: Information collection rule (issued

under section 1412(b) of the SDWA)ILSI: International Life Sciences

InstituteIESTWR: Interim Enhanced Surface

Water Treatment RuleLOAEL: Lowest Observed Adverse

Effect LevelLT1ESTWR: Long-Term 1Enhanced

Surface Water Treatment RuleMCL: Maximum contaminant levelMCLG: Maximum contaminant level

goalM–DBP: Microbial and Disinfectants/

Disinfection Byproductsmg/L: Milligrams per literMRDL: Maximum residual disinfectant

levelMRDLG: Maximum residual disinfectant

level goalNDWAC: National Drinking Water

Advisory CouncilNIST: National Institute of Science and

TechnologyNOAEL: No Observed Adverse Effect

LevelNODA: Notice of Data AvailabilityNOM: Natural organic matterNPDWR: National Primary Drinking

Water RegulationNTNCWS: Nontransient noncommunity

water systemNTP: National Toxicology ProgramNTTAA: National Technology Transfer

and Advancement ActNTU: Nephelometric turbidity unitOMB: Office of Management and BudgetPAR: Population attributable riskPBMS: Performance based measurement

systemPE: Performance evaluationPODR: Point of diminishing returnPQL: Practical quantitation limitPWS: Public water systemQC: Quality controlReg. Neg.: Regulatory NegotiationRFA: Regulatory Flexibility ActRfD: Reference doseRIA: Regulatory impact analysisRSC: Relative source contributionSAB: Science Advisory BoardSBREFA: Small Business Regulatory

Enforcement Fairness ActSDWIS: Safe Drinking Water

Information SystemSUVA: Specific ultraviolet absorbanceSDWA: Safe Drinking Water Act, or the

‘‘Act,’’ as amended 1996SWTR: Surface Water Treatment RuleTC: Total coliformsTCA: Trichloroacetic acidTCR: Total Coliform RuleTOC: Total organic carbonTOX: Total organic halidesTTHM: Total trihalomethanes

(chloroform, bromdichloromethane,dibromochloromethane, andbromoform)

TNCWS: Transient noncommunitywater systems

TWG: Technical work groupUMRA: Unfunded mandates reform actURTH: Unreasonable risk to healthWIDB: Water Industry Data Base

Table of Contents

I. BackgroundA. Statutory Requirements and Legal

AuthorityB. Regulatory History1. Existing Regulations2. Public Health Concerns To Be

Addressed3. Regulatory Negotiation Process4. Federal Advisory Committee Process5. 1997 and 1998 Notices of Data

Availability (NODA)II. Summary of Final Stage 1 Disinfection

Byproduct RuleA. ApplicabilityB. MRDLGs and MRDLs for DisinfectantsC. MCLGs and MCLs for TTHMs, HAA5,

Chlorite, and BromateD. Treatment Technique for Disinfection

Byproducts PrecursorsE. BAT for Disinfectants, TTHMs, HAA5,

Chlorite, and BromateF. Compliance Monitoring RequirementsG. Analytical MethodsH. Laboratory Certification CriteriaI. Variances and ExemptionsJ. State Recordkeeping, Primacy, Reporting

RequirementsK. System Reporting RequirementsL. Guidance ManualsM. Regulation Review

III. Explanation of Final RuleA. MCLGs/MRDLGs1. MCLG for Chloroforma. Today’s Ruleb. Background and Analysisc. Summary of Comments2. MCLG for Bromodichloromethane

(BDCM)a. Today’s Ruleb. Background and Analysisc. Summary of Comments3. MCLG for Dibromochloromethane

(DBCM)a. Today’s Ruleb. Background and Analysisc. Summary of Comments4. MCLG for Bromoforma. Today’s Ruleb. Background and Analysisc. Summary of Comments5. MCLG for Dichloroacetic Acid (DCA)a. Today’s Ruleb. Background and Analysisc. Summary of Comments6. MCLG for Trichloroacetic Acid (TCA)a. Today’s Ruleb. Background and Analysisc. Summary of Comments7. MCLG for Chlorite and MRDLG for

Chlorine Dioxidea. Today’s Ruleb. Background and Analysisc. Summary of Comments8. MCLG for Bromatea. Today’s Ruleb. Background and Analysisc. Summary of Comments


9. MCLG for Chloral Hydratea. Today’s Ruleb. Background and Analysisc. Summary of Comments10. MRDLG for Chlorinea. Today’s Ruleb. Background and Analysisc. Summary of Comments11. MRDLG for Chloraminea. Today’s Ruleb. Background and Analysisc. Summary of CommentsB. Epidemiology1. Cancer Epidemiologya. Today’s Ruleb. Background and Analysisc. Summary of Comments2. Reproductive and Developmental

Epidemiologya. Today’s Ruleb. Background and Analysisc. Summary of CommentsC. MCLs and BAT for TTHM, HAA5,

Chlorite, and Bromate; MRDLs and BATfor Chlorine, Chloramines, and ChlorineDioxide

1. MCLs for TTHMs and HAA5a. Today’s Ruleb. Background and Analysisc. Summary of Comments2. MCL for Bromatea. Today’s Ruleb. Background and Analysisc. Summary of Comments3. MCL for Chloritea. Today’s Ruleb. Background and Analysisc. Summary of Comments4. MRDL for Chlorinea. Today’s Ruleb. Background and Analysisc. Summary of Comments5. MRDL for Chloraminesa. Today’s Ruleb. Background and Analysisc. Summary of Comments6. MRDL for Chlorine Dioxidea. Today’s Ruleb. Background Analysisc. Summary of CommentsD. Treatment Technique Requirement1. Today’s Rule2. Background and Analysis3. Summary of CommentsE. Predisinfection Disinfection Credit1. Today’s Rule2. Background and Analysis3. Summary of CommentsF. Requirements for Systems to Use

Qualified OperatorsG. Analytical Methods1. Today’s Rule2. Background and Analysis3. Summary of Comments4. Performance Based Measurement

SystemsH. Monitoring Requirements1. Today’s Rule2. Background and Analysis3. Summary of CommentsI. Compliance Schedules1. Today’s Rule2. Background and Analysis3. Summary of CommentsJ. Public Notice Requirements1. Today’s Rule

2. Background and Analysis3. Summary of CommentsK. System Reporting and Record Keeping

Requirements1. Today’s Rule2. Summary of CommentsL. State Recordkeeping, Primacy, and

Reporting Requirements1. State Recordkeeping Requirementsa. Today’s Ruleb. Background and Analysisc. Summary of Comments2. Special Primacy Requirementsa. Today’s Ruleb. Background and Analysisc. Summary of Comments3. State Reporting Requirementsa. Today’s Ruleb. Background and Analysisc. Summary of CommentsM. Variances and Exemptions1. Today’s Rule2. Background and Analysis3. Summary of CommentsN. Laboratory Certification and Approval1. Today’s Rule2. Background and Analysis3. Summary of Comments

IV. Economic AnalysisA. Today’s RuleB. Background1. Overview of RIA for the Proposed Rule2. Factors Affecting Changes to the 1994

RIAa. Changes in Rule Criteriab. New Information Affecting DBP

Occurrence and Compliance Forecastc. New Epidemiology InformationC. Cost Analysis1. Revised Compliance Forecast2. System Level Unit Costs3. National CostsD. Benefits Analysis1. Exposure Assessment2. Baseline Risk Assessment Based on

TTHM Toxicological Data3. Baseline Analysis Based on

Epidemiology Data4. Exposure Reduction Analysis5. Monetization of Health EndpointsE. Net Benefits AnalysisF. Summary of Comments

V. Other RequirementsA. Regulatory Flexibility Analysis1. Today’s Rule2. Background and Analysis3. Summary of CommentsB. Paperwork Reduction ActC. Unfunded Mandates Reform Act1. Summary of UMRA Requirements2. Written Statement for Rules with Federal

Mandates of $100 million or Morea. Authorizing Legislationb. Cost Benefit Analysisc. Estimates of Future Compliance Costs

and Disproportionate Budgetary Effectsd. Macro-economic Effectse. Summary of State, Local, and Tribal

Government and TheirConcernsf. Regulatory Alternative Considered3. Impacts on Small GovernmentsD. National Technology Transfer and

Advancement ActE. Executive Order 12866: Regulatory

Planning and ReviewF. Executive Order 12898: Environmental

Justice

G. Executive Order 13045: Protection ofChildren from Environmental HealthRisks and Safety Risks

H. Consultation with the Science AdvisoryBoard, National Drinking WaterAdvisory Council, and the Secretary ofHealth and Human Services

I. Executive Order 12875: Enhancing theIntergovernmental Partnership

J. Executive Order 13084: Consultation andCoordination with Indian TribalGovernments

K. Submission to Congress and the GeneralAccounting Office

L. Likely Effect of Compliance with theStage 1 DBPR on the Technical,Financial, and Managerial Capacity ofPublic Water Systems

VI. References

I. Background

A. Statutory Requirements and LegalAuthority

The Safe Drinking Water Act (SDWAor the Act), as amended in 1986,requires USEPA to publish a ‘‘maximumcontaminant level goal’’ (MCLG) foreach contaminant which, in thejudgement of the USEPA Administrator,‘‘may have any adverse effect on thehealth of persons and which is knownor anticipated to occur in public watersystems’’ (Section 1412(b)(3)(A)).MCLGs are to be set at a level at which‘‘no known or anticipated adverse effecton the health of persons occur andwhich allows an adequate margin ofsafety’’ (Section 1412(b)(4)).

The Act was amended in August1996. As a result of these Amendments,several of these provisions wererenumbered and augmented withadditional language. Other sectionswere added establishing new drinkingwater requirements. Thesemodifications are outlined below.

The Act also requires that at the sametime USEPA publishes an MCLG, whichis a non-enforceable health goal, it alsomust publish a National PrimaryDrinking Water Regulation (NPDWR)that specifies either a maximumcontaminant level (MCL) or treatmenttechnique (Sections 1401(1) and1412(a)(3)). USEPA is authorized topromulgate a NPDWR ‘‘that requires theuse of a treatment technique in lieu ofestablishing a MCL,’’ if the Agency findsthat ‘‘it is not economically ortechnologically feasible to ascertain thelevel of the contaminant’’.

As amended, EPA’s general authorityto set a maximum contaminant levelgoal (MCLG) and National PrimaryDrinking Water Regulation (NPDWR)applies to contaminants that may ‘‘havean adverse effect on the health ofpersons,’’ that are ‘‘known to occur orthere is a substantial likelihood that thecontaminant will occur in public water


systems with a frequency and at levelsof public health concern,’’ and forwhich ‘‘in the sole judgement of theAdministrator, regulation of suchcontaminant presents a meaningfulopportunity for health risk reduction forpersons served by public watersystems’’ (SDWA Section 1412(b)(1)(A)).

The amendments, also require EPA,when proposing a NPDWR that includesan MCL or treatment technique, topublish and seek public comment on ananalysis of health risk reduction andcost impacts. In addition, EPA isrequired to take into consideration theeffects of contaminants upon sensitivesubpopulations (i.e. infants, children,pregnant women, the elderly, andindividuals with a history of seriousillness), and other relevant factors.(Section 1412 (b)(3)(C)).

The amendments established anumber of regulatory deadlines,including schedules for a Stage 1Disinfection Byproduct Rule (DBPR), anInterim Enhanced Surface WaterTreatment Rule (IESWTR), a Long-TermFinal Enhanced Surface WaterTreatment Rule (LTESWTR) affectingPublic Water Systems (PWSs) that serveunder 10,000 people, and a Stage 2DBPR (Section 1412(b)(2)(C)). The Actas amended also requires EPA topromulgate regulations to address filterbackwash (Section 1412(b)(14)). Finally,the Act requires EPA to promulgateregulations specifying criteria forrequiring disinfection ‘‘as necessary’’ forground water systems (Section 1412(b)(8)).

Finally, as part of the 1996 SDWAAmendments, recordkeepingrequirements were modified to apply to‘‘every person who is subject to arequirement of this title or who is agrantee’’ (Section 1445 (a)(1)(A)). Suchpersons are required to ‘‘establish andmaintain such records, make suchreports, conduct such monitoring, andprovide such information as theAdministrator may reasonably requireby regulation * * * ’’.

B. Regulatory History

1. Existing Regulations

Surface Water Treatment Rule. Underthe Surface Water Treatment Rule(SWTR) (54 FR 27486, June 29, 1989)(EPA,1989a), EPA set maximumcontaminant level goals of zero forGiardia lamblia, viruses, and Legionella;and promulgated NPDWR for all PWSsusing surface water sources or groundwater sources under the direct influenceof surface water. The SWTR includestreatment technique requirements forfiltered and unfiltered systems that areintended to protect against the adverse

health effects of exposure to Giardialamblia, viruses, and Legionella, as wellas many other pathogenic organisms.Briefly, those requirements include: (1)requirements for a maintenance of adisinfectant residual in the distributionsystem; (2) removal and/or inactivationof 3 logs (99.9%) for Giardia and 4 logs(99.99%) for viruses; (3) combined filtereffluent performance of 5 nephelometricturbidity unit (NTU) as a maximum and0.5 NTU at 95th percentile monthly,based on 4-hour monitoring fortreatment plants using conventionaltreatment or direct filtration (withseparate standards for other filtrationtechnologies); and (4) watershedprotection and other requirements forunfiltered systems.

Total Coliform Rule. The TotalColiform Rule (TCR) (54 FR 27544; June29, 1989) applies to all public watersystems (EPA, 1989b). This regulationsets compliance with the MCL for totalcoliforms (TC) as follows. For systemsthat collect 40 or more samples permonth, no more than 5.0% of thesamples may be TC-positive; for thosethat collect fewer than 40 samples, nomore than one sample may be TC-positive. In addition, if two consecutivesamples in the system are TC-positive,and one is also fecal coliform or E. coli-positive, then this is defined as an acuteviolation of the MCL. If a systemexceeds the MCL, it must notify thepublic using mandatory languagedeveloped by the EPA. The requiredmonitoring frequency for a systemdepends on the number of peopleserved and, ranges from 480 samples permonth for the largest systems to onceannually for certain of the smallestsystems. All systems must have awritten plan identifying where samplesare to be collected.

If a system has a TC-positive sample,it must test that sample for the presenceof fecal coliforms or E. coli. The systemmust also collect a set of repeat samples,and analyze for TC (and fecal coliformor E. coli) within 24 hours of the firstTC-positive sample.

The TCR also requires an on-siteinspection every 5 years (10 years fornon-community systems using onlyprotected and disinfected ground water)for each system that collects fewer thanfive samples per month. This on-siteinspection (referred to as a sanitarysurvey) must be performed by the Stateor by an agent approved by the State.

Total Trihalomethane Rule. InNovember 1979 (44 FR 68624) (EPA,1979) EPA set an interim MCL for totaltrihalomethanes (TTHM) of 0.10milligrams per liter (mg/L) as an annualaverage. Compliance is defined on thebasis of a running annual average of

quarterly averages of all samples. Thevalue for each sample is the sum of themeasured concentrations of chloroform,bromodichloromethane (BDCM),dibromochloromethane (DBCM) andbromoform.

The interim TTHM standard onlyapplies to community water systemsusing surface water and/or ground waterserving at least 10,000 people that adda disinfectant to the drinking waterduring any part of the treatment process.At their discretion, States may extendcoverage to smaller PWSs; however,most States have not exercised thisoption.

Information Collection Rule. TheInformation Collection Rule (ICR) is amonitoring and data reporting rule thatwas promulgated on May 14, 1996 (61FR 24354) (EPA, 1996a). The purpose ofthe ICR is to collect occurrence andtreatment information to help evaluatethe need for possible changes to thecurrent SWTR and existing microbialtreatment practices, and to help evaluatethe need for future regulation fordisinfectants and disinfectionbyproducts (D/DBPs). The ICR willprovide EPA with additionalinformation on the national occurrencein drinking water of (1) chemicalbyproducts that form when disinfectantsused for microbial control react withnaturally occurring compounds alreadypresent in source water and (2) disease-causing microorganisms, includingCryptosporidium, Giardia, and viruses.The ICR will also provide engineeringdata on how PWSs currently control forsuch contaminants. This information isbeing collected because the 1992Regulatory Negotiating Committee(henceforth referred to as the Reg. Neg.Committee) on microbial pathogens anddisinfectants and DBPs concluded thatadditional information was needed toassess the potential health problemcreated by the presence of DBPs andpathogens in drinking water and toassess the extent and severity of risk inorder to make sound regulatory andpublic health decisions. The ICR willalso provide information to supportregulatory impact analyses for variousregulatory options, and to help developmonitoring strategies for cost-effectivelyimplementing regulations.

The ICR pertains to large public watersystems serving populations at least100,000; a more limited set of ICRrequirements pertain to ground watersystems serving between 50,000 and100,000 people. About 300 PWSsoperating 500 treatment plants areinvolved with the extensive ICR datacollection. Under the ICR, these PWSsmonitor for water quality factorsaffecting DBP formation and DBPs


within the treatment plant and in thedistribution system monthly for 18months. In addition, PWSs mustprovide operating data and a descriptionof their treatment plan design andsurface water systems must monitor forbacteria, viruses, and protozoa. Finally,a subset of PWSs must performtreatment studies, using either granularactivated carbon (GAC) or membraneprocesses, to evaluate DBP precursorremoval and control of DBPs.Monitoring for treatment studyapplicability began in September 1996.The remaining occurrence monitoringbegan in July 1997.

One initial intent of the ICR was tocollect pathogen occurrence data andother information for use in developingthe IESWTR and to estimate nationalcosts for various treatment options.However, because of delays inpromulgating the ICR and technicaldifficulties associated with laboratoryapproval and review of facility samplingplans, ICR monitoring did not beginuntil July 1, 1997, which was later thanoriginally anticipated. As a result of thisdelay and the new statutory deadlinesfor promulgating the Stage 1 DBPR andIESWTR in November of 1998 (resultingfrom the 1996 SDWA amendments), ICRdata were not available in time tosupport these rules. In place of the ICRdata, the Agency worked withstakeholders to identify other sources ofdata developed since 1994 that could beused to support the development of theStage 1 DBPR and IESWTR. EPA willcontinue to work with stakeholders inanalyzing and using the comprehensiveICR data and research for developingfuture Enhanced Surface WaterTreatment requirements and the Stage 2DBPR.

2. Public Health Concerns to beAddressed

EPA’s main mission is the protectionof human health and the environment.When carrying out this mission, EPAmust often make regulatory decisionswith less than complete information andwith uncertainties in the availableinformation. EPA believes it isappropriate and prudent to err on theside of public health protection whenthere are indications that exposure to acontaminant may present risks to publichealth, rather than take no action untilrisks are unequivocally proven.

In regard to the Stage 1 DBPR, EPArecognizes that the assessment of publichealth risks from disinfection ofdrinking water currently relies oninherently difficult and preliminaryempirical analysis. On one hand,epidemiologic studies of thepopulations in various geographic areas

are hampered by difficulties of studydesign, scope, and sensitivity. On theother hand, uncertainty is involved inthe interpretation of results using highdose animal toxicological studies of afew of the numerous byproducts thatoccur in disinfected drinking water toestimate the risk to humans fromchronic exposure to low doses of theseand other byproducts. Such studies ofindividual DBPs is insufficient tocharacterize risks from exposure to theentire mixture of DBPs in disinfecteddrinking water. While recognizing theseuncertainties, EPA continues to believethat the Stage 1 DBPR is necessary forthe protection of public health fromexposure to potentially harmful DBPs.

A fundamental component inassessing the risk for a contaminant isthe number of people that may beexposed to the parameter of concern. Inthis case, there is a very largepopulation potentially exposed to DBPsthrough drinking water in the U.S. Over200 million people are served by PWSsthat apply a disinfectant (e.g., chlorine)to water in order to provide protectionagainst microbial contaminants. Whilethese disinfectants are effective incontrolling many microorganisms, theyreact with natural organic and inorganicmatter in the water to form DBPs, someof which may pose health risks. One ofthe most complex questions facingwater supply professionals is how tominimize the risks from DBPs and stillmaintain adequate control overmicrobial contaminants. Because of thelarge number of people exposed toDBPs, there is a substantial concern forany risks associated with DBPs that mayimpact public health.

Since the discovery of chlorinationbyproducts in drinking water in 1974,numerous toxicological studies havebeen conducted. Results from thesestudies have shown several DBPs (e.g.,bromodichloromethane, bromoform,chloroform, dichloroacetic acid, andbromate) to be carcinogenic inlaboratory animals . Some DBPs (e.g.,chlorite, BDCM, and certain haloaceticacids) have also been shown to causeadverse reproductive or developmentaleffects in laboratory animals. Althoughmany of these studies have beenconducted at high doses, EPA believesthe studies provide evidence that DBPspresent a potential public health riskthat needs to be addressed.

In the area of epidemiology, a numberof epidemiology studies have beenconducted to investigate therelationship between exposure tochlorinated surface water and cancer.While EPA cannot conclude there is acausal link between exposure tochlorinated surface water and cancer,

these studies have suggested anassociation, albeit small, betweenbladder, rectal, and colon cancer andexposure to chlorinated surface water.While there are fewer publishedepidemiology studies that have beenconducted to evaluate the possiblerelationship between exposure tochlorinated surface water andreproductive and developmental effects,a recent study has suggested anassociation between early termmiscarriage and exposure to drinkingwater with elevated trihalomethanelevels. In addition to this study, anothernew study reported a small increasedrisk of neural tube defects associatedwith consumption of drinking watercontaining high levels of TTHMs.However, no significant associationswere observed with individual THMs,HAAs, and haloacetonitriles (HANs)and adverse outcomes in this study. Aswith cancer, EPA cannot conclude atthis time there is a causal link betweenexposure to DBPs and reproductive anddevelopmental effects.

While EPA recognizes there are datadeficiencies in the information on thehealth effects from the DBPs and thelevels at which they occur, the Agencybelieves the weight-of-evidencepresented by the availableepidemiological studies on chlorinateddrinking water and toxicological studieson individual DBPs support a potentialhazard concern and warrant regulatoryaction at this time to reduce DBP levelsin drinking water. Recognizing thedeficiencies in the existing data, EPAbelieves the incremental two-stageapproach for regulating DBPs, agreedupon by the regulatory negotiationprocess, is prudent and necessary toprotect public health and meet therequirements of the SDWA.

In conclusion, because of the largenumber of people exposed to DBPs andthe different potential health risks (e.g.,cancer and adverse reproductive anddevelopmental effects) that may resultfrom exposure to DBPs, EPA believesthe Stage 1 DBPR is needed to furtherprevent potential health effects fromDBPs, beyond that controlled for by the1979 total trihalomethane rule. Both theReg. Neg. Committee for the 1994proposed rule and the Microbial andDisinfectants/Disinfection ByproductsAdvisory Committee (henceforth citedas the M-DBP Advisory Committee)formed in March 1997 under the FederalAdvisory Committee Act (FACA),agreed with the need for the Stage 1DBPR to reduce potential risks fromDBPs in the near term, whileacknowledging additional informationis still needed for the Stage 2 DBPR(especially on health effects),


3. Regulatory Negotiation Process

In 1992 EPA initiated a negotiatedrulemaking to address public healthconcerns associated with disinfectants,DBPs, and microbial pathogens. Thenegotiators included representatives ofState and local health and regulatoryagencies, public water systems, electedofficials, consumer groups andenvironmental groups. The Reg. Neg.Committee met from November 1992through June 1993.

Early in the process, the negotiatorsagreed that large amounts of informationnecessary to understand how tooptimize the use of disinfectants toconcurrently minimize microbial andDBP risk on a plant-specific basis wereunavailable. Nevertheless, the Reg. Neg.Committee agreed that EPA propose aStage 1 DBPR to extend coverage to allcommunity and nontransientnoncommunity water systems that usedisinfectants, reduce the current TTHMMCL, regulate additional DBPs, setlimits for the use of disinfectants, andreduce the level of organic precursorcompounds in the source water thatmay react with disinfectants to formDBPs.

EPA’s most significant concern indeveloping regulations for disinfectantsand DBPs was the need to ensure thatadequate treatment be maintained forcontrolling risks from microbialpathogens. One of the major goalsaddressed by the Reg. Neg. Committeewas to develop an approach that wouldreduce the level of exposure fromdisinfectants and DBPs withoutundermining the control of microbialpathogens. The intention was to ensurethat drinking water is microbiologicallysafe at the limits set for disinfectantsand DBPs and that these chemicals donot pose an unacceptable health risk atthese limits. Thus, the Reg. Neg.Committee also considered a range ofmicrobial issues and agreed that EPAshould also propose a companionmicrobial rule (IESWTR).

Following months of intensivediscussions and technical analysis, theReg. Neg. Committee recommended thedevelopment of three sets of rules: atwo-staged approach for the DBPs(proposal: 59 FR 38668, July 29, 1994)(EPA, 1994a), an ‘‘interim’’ ESWTR(proposal: 59 FR 38832, July 29, 1994)(EPA, 1994b), and an informationcollection rule (proposal: 59 FR 6332,February 10, 1994) (EPA, 1994c)(promulgation: 61FR24354, May 14,1996) (EPA, 1996a). The approach usedin developing these proposalsconsidered the constraints ofsimultaneously treating water to control

for both microbial contaminants and D/DBPs.

The Reg. Neg. Committee agreed thatthe schedules for IESWTR andLTESWTR should be ‘‘linked’’ to theschedule for the Stage 1 DBPR to assuresimultaneous compliance and abalanced risk-risk basedimplementation. The Reg. Neg.Committee agreed that additionalinformation on health risk, occurrence,treatment technologies, and analyticalmethods needed to be developed inorder to better understand the risk-risktradeoff, and how to accomplish anoverall reduction in health risks to bothpathogens and D/DBPs.

Finally the Reg. Neg. Committeeagreed that to develop a reasonable setof rules and to understand more fullythe limitations of the current SWTR,additional field data were critical. Thus,a key component of the regulationnegotiation agreement was thepromulgation of the ICR previouslydescribed.

4. Federal Advisory Committee ProcessIn May 1996, the Agency initiated a

series of public informational meetingsto provide an update on the status of the1994 proposal and to review new datarelated to microbial and DBP regulationsthat had been developed since July1994. In August 1996, Congress enactedthe 1996 SDWA Amendments whichcontained a number of newrequirements, as discussed above, aswell as specifying deadlines for finalpromulgation of the IESWTR and Stage1 DBPR. To meet these deadlines and tomaximize stakeholder participation, theAgency established the M–DBPAdvisory Committee under FACA inMarch 1997, to collect, share, andanalyze new information and data, aswell as to build consensus on theregulatory implications of this newinformation. The Committee consistedof 17 members representing EPA, Stateand local public health and regulatoryagencies, local elected officials, drinkingwater suppliers, chemical andequipment manufacturers, and publicinterest groups.

The M–DBP Advisory Committee metfive times in March through July 1997to discuss issues related to the IESWTRand Stage 1 DBPR. Technical supportfor these discussions was provided by aTechnical Work Group (TWG)established by the Committee at its firstmeeting in March 1997. TheCommittee’s activities resulted in thecollection, development, evaluation,and presentation of substantial new dataand information related to key elementsof both proposed rules. The Committeereached agreement on a number of

major issues that were discussed inNotices of Data Availability (NODA) forthe IESWTR (62 FR 59486, November 3,1997) (EPA, 1997a) and the Stage 1DBPR (62 FR 59388, November 3, 1997)(EPA, 1997b). The majorrecommendations addressed by theCommittee and in the NODAs were to:(1) Maintain the proposed MCLs forTTHM, HAA5, and bromate; (2) modifythe enhanced coagulation requirementsas part of DBP control; (3) include amicrobial benchmarking/profiling toprovide a methodology and process bywhich a PWS and the State, workingtogether, assure that there will be nosignificant reduction in microbialprotection as the result of modifyingdisinfection practices in order to meetMCLs for TTHM and HAA5; (4)continue credit for compliance withapplicable disinfection requirements fordisinfection applied at any point priorto the first customer, consistent with theexisting SWTR; (5) modify the turbidityperformance requirements and addrequirements for individual filters; (6)establish an MCLG for Cryptosporidium;(7) add requirements for removal ofCryptosporidium; (8) provide formandatory sanitary surveys; and (9)make a commitment to additionalanalysis of the role of Cryptosporidiuminactivation as part of a multiple barrierconcept in the context of a subsequentFederal Register microbial proposal. Thenew data and analysis supporting thetechnical areas of agreement weresummarized and explained at length inEPA’s 1997 NODAs (EPA, 1997a andEPA, 1997b).

5. 1997 and 1998 Notices of DataAvailability

In November 1997 EPA published aNODA (USEPA, 1997b) thatsummarized the 1994 proposal;described new data and information thatthe Agency has obtained and analysesthat have been developed since theproposal; provided informationconcerning the July 1997recommendations of the M–DBPAdvisory Committee on key issuesrelated to the proposal (describedabove); and requested comment on theserecommendations, as well as on otherregulatory implications that flow fromthe new data and information. TheAgency solicited additional data andinformation that were relevant to theissues discussed in the DBP NODA. EPAalso requested that any information theAgency should consider as part of thefinal rule development processregarding data or views submitted to theAgency since the close of the commentperiod on the 1994 proposal, beformally resubmitted during the 90-day


comment period unless already in theunderlying record in the docket for theNODA.

In March 1998, EPA issued a secondDBP NODA (EPA, 1998a) thatsummarized new health effectsinformation received and analyzed sincethe November 1997 NODA andrequested comments on several issuesrelated to the simultaneous compliancewith the Stage 1 DBPR and the Lead andCopper Rule. The 1998 NODA indicatedEPA was considering increasing theMCLG for chloroform from zero to 0.3mg/L and the proposed MCLG forchlorite from 0.08 mg/L to 0.8 mg/L.EPA also requested comment on

increasing the Maximum ResidualDisinfection Level Goal (MRDLG) forchlorine dioxide from 0.3 mg/L to 0.8mg/L. Today’s final rule was developedbased on the outcome of the 1992 Reg.Neg., the 1994 proposed rule, the 1997FACA process, and both the 1997 and1998 DBP NODAs, as well as a widerange of technical comments fromstakeholders and members of the public.A summary of today’s rule follows.

II. Summary of Final Stage 1Disinfection Byproduct Rule

A. ApplicabilityThe final Stage 1 DBPR applies to

community water systems (CWSs) and

nontransient noncommunity watersystems (NTNCWs) that treat their waterwith a chemical disinfectant for eitherprimary or residual treatment. Inaddition, certain requirements forchlorine dioxide apply to transientnoncommunity water systems(TNCWSs).

B. MRDLGs and MRDLs for Disinfectants

EPA is finalizing the followingMRDLGs and maximum residualdisinfectant levels (MRDLs) for chlorine,chloramines, and chlorine dioxide inTable II–1.

TABLE II–1.—MRDLGS AND MRDLS FOR DISINFECTANTS

Disinfectant residual MRDLG (mg/L) MRDL (mg/L)

Chlorine ..................................................................................................................................................... 4 (as Cl2) 4.0 (as Cl2)Chloramine ................................................................................................................................................ 4 (as Cl2) 4.0 (as Cl2)Chlorine Dioxide ........................................................................................................................................ 0.8 (as ClO2) 0.8 (as ClO2)

C. MCLGs and MCLs for TTHMs, HAA5,Chlorite, and Bromate

EPA is finalizing the MCLGs andMCLs in Table II–2.

TABLE II–2.—MCLGS AND MCLS FOR DISINFECTION BYPRODUCTS

Disinfection byproducts MCLG (mg/L) MCL (mg/L)

Total trihalomethanes (TTHM) 1 ................................................................................................................................... N/A 0.080—Chloroform ......................................................................................................................................................... 0 ......................—Bromodichloromethane ..................................................................................................................................... 0 ......................—Dibromochloromethane ..................................................................................................................................... 0.06 ......................—Bromoform ......................................................................................................................................................... 0 ......................

Haloacetic acids (five) (HAA5) 2 ................................................................................................................................... N/A 0.060—Dichloroacetic acid ............................................................................................................................................ 0 ......................—Trichloroacetic acid ........................................................................................................................................... 0.3 ......................

Chlorite ......................................................................................................................................................................... 0.8 1.0Bromate ........................................................................................................................................................................ 0 0.010

N/A—Not applicable because there are no individual MCLGs for TTHMs or HAAs.1 Total trihalomethanes is the sum of the concentrations of chloroform, bromodichloromethane, dibromochloromethane, and bromoform.2 Haloacetic acids (five) is the sum of the concentrations of mono-, di-, and trichloroacetic acids and mono- and dibromoacetic acids.

D. Treatment Technique for DisinfectionByproduct Precursors

Water systems that use surface wateror ground water under the directinfluence of surface water and use

conventional filtration treatment arerequired to remove specifiedpercentages of organic materials(measured as total organic carbon) thatmay react with disinfectants to formDBPs as indicated in Table II–3.

Removal will be achieved through atreatment technique (enhancedcoagulation or enhanced softening)unless a system meets alternativecriteria discussed in Section III.D.

TABLE II–3.—REQUIRED REMOVAL OF TOTAL ORGANIC CARBON BY ENHANCED COAGULATION AND ENHANCED SOFTENINGFOR SUBPART H SYSTEMS USING CONVENTIONAL TREATMENT a,b,c

Source Water TOC (mg/L)

Source Water Alkalinity (mg/L asCaCO3) (percent)

0–60 >60–120 >120

>2.0–4.0 ................................................................................................................................................... 35.0 25.0 15.0>4.0–8.0 ................................................................................................................................................... 45.0 35.0 25.0


TABLE II–3.—REQUIRED REMOVAL OF TOTAL ORGANIC CARBON BY ENHANCED COAGULATION AND ENHANCED SOFTENINGFOR SUBPART H SYSTEMS USING CONVENTIONAL TREATMENT a,b,c—Continued

Source Water TOC (mg/L)

Source Water Alkalinity (mg/L asCaCO3) (percent)

0–60 >60–120 >120

>8.0 .......................................................................................................................................................... 50.0 40.0 30.0

a Systems meeting at least one of the conditions in Section 141.135(a)(2) (i)–(vi) of the rule are not required to operate the removals in thistable.

b Softening systems meeting one of the two alternative compliance criteria in Section 141.135(a)(3) of the rule are not required to meet the re-movals in this table.

c Systems practicing softening must meet the TOC removal requirements in the last column to the right.

E. BAT for Disinfectants, TTHMs,HAA5, Chlorite, and Bromate

Under the SDWA, EPA must specifythe BAT for each MCL (or MRDL) that

is set. PWS that are unable to achieve anMCL or MRDL may be granted avariance if they use the BAT and meetother requirements (see section III.M fora discussion of variances and

exemptions). Table II.4 includes theBATs for each of the MCLs or MRDLsthat EPA is promulgating in today’sStage 1 DBPR.

TABLE II–4.—BAT FOR DISINFECTANTS AND DISINFECTION BYPRODUCTS

Disinfectant/DBP Best available technology

Disinfectants

Chlorine residual .................. Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes toreduce disinfectant levels.

Chloramine residual ............. Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes toreduce disinfectant levels.

Chlorine dioxide residual ...... Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes toreduce disinfectant levels.

Disinfection Byproducts

Total trihalomethanes ........... Enhanced coagulation or enhanced softening or GAC10*, with chlorine as the primary and residual disinfectant.Total haloacetic acids ........... Enhanced coagulation or enhanced softening or GAC10*, with chlorine as the primary and residual disinfectant.Chlorite ................................. Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes to

reduce disinfectant levels.Bromate ................................ Control of ozone treatment process to reduce production of bromate.

* GAC10 means granular activated carbon with an empty bed contact time of 10 minutes and reactivation frequency for GAC of no more thansix months.

F. Compliance Monitoring Requirements

Compliance monitoring requirementsare explained in Section III.H of today’srule. EPA has developed routine andreduced compliance monitoringschemes for disinfectants and DBPs tobe protective from different types ofhealth concerns, including acute andlong-term effects.

G. Analytical Methods

EPA has approved five methods formeasurement of free chlorine, fourmethods for combined chlorine, and sixfor total chlorine. EPA has alsoapproved two methods for themeasurement of chlorine dioxideresiduals; three methods for themeasurement of HAA5; three methodsfor the measurement of TTHMs; threemethods for the measurement of TOC/Dissolved Organic Carbon (DOC); twomethods for the monthly measurementof chlorite and one method for the daily

monitoring of chlorite; two methods forbromide; one method for themeasurement of bromate; and onemethod for the measurement of UV254.Finally, EPA approved all methodsallowed in § 141.89(a) for measuringalkalinity. These issues are discussed inmore detail in section III.G.

H. Laboratory Certification Criteria

Consistent with other drinking waterregulations, determinations ofcompliance with the MCLs may only beconducted by certified laboratories. EPAis requiring that analyses can beconducted by a party acceptable to EPAor the State in those situations wherethe parameter can adequately bemeasured by someone other than acertified laboratory and for which thereis a good reason to allow analysis atother locations (e.g., for samples whichnormally deteriorate before reaching acertified laboratory, especially whentaken at remote locations). For a

detailed discussion of the labcertification requirements, see sectionIII.N.

I. Variances and Exemptions

Variances and exemptions will bepermitted in accordance with existingstatutory and regulatory authority. For adetailed discussion see section III.M.

J. State Recordkeeping, Primacy, andReporting Requirements

The Stage 1 DBPR requires States toadopt several regulatory requirements,including public notificationrequirements, MCLs for DBPs, MRDLsfor disinfectants, and the requirementsin Subpart L. In addition, States arerequired to adopt several specialprimacy requirements for the Stage 1DPBR. States are also required to keepspecific records in accordance withexisting regulations and additionalrecords specific to the Stage 1 DBPR.Finally, the rule does not require any


State additional reporting requirementsbeyond those required under existingregulations. These requirements arediscussed in more detail in Section III.L.

K. System Reporting RequirementsSystem are required to report

monitoring data to the State asdiscussed in Section III.K.

L. Guidance ManualsEPA is developing guidance for both

systems and States for theimplementation of the Stage 1 DBPRand the IESWTR. The guidance manualsinclude: Guidance Manual for EnhancedCoagulation and Precipitative Softening;Disinfection Benchmark GuidanceManual; Turbidity Guidance Manual;Alternative Disinfectants and OxidantsGuidance Manual; M/DBP SimultaneousCompliance Manual; Sanitary SurveyGuidance Manual; Unfiltered SystemsGuidance Manual; and UncoveredFinished Water Reservoirs. Guidancemanuals will be available after thepublication of the Stage 1 DBPR.

M. Regulation ReviewUnder the provisions of the SDWA

(Section 1412(b)(9)), the Agency isrequired to review NPDWRs at leastonce every six years. As mentionedpreviously, today’s final rule revises,updates, and supersedes the regulationsfor total trihalomethanes, initiallypublished in 1979. Since that time,there have been significant changes intechnology, treatment techniques, andother regulatory controls that providefor greater protection of human health.As such, for today’s rule, EPA hasanalyzed innovations and changes intechnology and treatment techniquesthat have occurred since promulgationof the interim TTHM regulations. Thatanalysis, contained primarily in the costand technology document supportingthis rule, supports the changes in theStage 1 DBPR from the 1979 TTHM rule.EPA believes that the innovations andchanges in technology and treatmenttechniques that result in changes to the1979 TTHM regulations are feasiblewithin the meaning of SDWA Section1412(b).

III. Explanation of Final Rule

A. MCLGs/MRDLGsMCLGs are set at levels at which no

known or anticipated adverse healtheffects occur, allowing for an adequatemargin of safety. Establishment of anMCLG for each specific contaminant isbased on the available evidence ofcarcinogenicity or noncancer adversehealth effects from drinking waterexposure using EPA’s guidelines for riskassessment (see the proposed rule at 59

FR 38677 for a detailed discussion ofthe process for establishing MCLGs).

The final Stage 1 DBPR containsMCLGs for: four THMs (chloroform,bromodichloromethane,dibromochloromethane, andbromoform); two haloacetic acids(dichloroacetic acid and trichloroaceticacid); bromate; and chlorite (see tableII–2 for final MCLG levels). TheseMCLGs are the same as those proposedin 1994 with the exception of chlorite,which increased from 0.08 mg/L to 0.8mg/L. The MCLG for chloral hydrate hasbeen dropped since EPA has concludedthat it will be controlled by the MCLsfor TTHM and HAA5 and the enhancedcoagulation treatment technique.

The final Stage 1 DBPR containsMRDLGs for chlorine, chloramines andchlorine dioxide (see table II–1 for finalMRDLG levels). The MRDLGs are as thesame as those proposed in 1994, withthe exception of chlorine dioxide,which increased from 0.3 mg/L to 0.8mg/L.

The MRDLG concept was introducedin the proposed rule for disinfectants toreflect the fact that these substanceshave beneficial disinfection properties.As with MCLGs, MRDLGs areestablished at the level at which noknown or anticipated adverse effects onthe health of persons occur and whichallows an adequate margin of safety.MRDLGs are nonenforceable healthgoals based only on health effects andexposure information and do not reflectthe benefit of the addition of thechemical for control for waterbornemicrobial contaminants. By using theterm ‘‘residual disinfectant’’ in lieu of‘‘contaminant’’, EPA intends to avoidsituations in which treatment plantoperators are reluctant to applydisinfectant dosages above the MRDLGduring short periods of time to controlfor microbial risk.

EPA received numerous comments onthe use of the term MRDLG. Themajority of commenters agreed that theterm MRDLG was appropriate to use inplace of MCLG for disinfectants. Othercommenters agreed, but felt that thelanguage should more strongly reflectthat disinfectants are necessary and thatshort-term exposure to elevated levels ofthe disinfectants is not a health concern.Some commenters suggested thatMRDLGs be extended to ozone,potassium permanganate and iodine.

In response, EPA agrees with themajority of commenters that the use ofthe term MRDLG is appropriate andtherefore the final rule retains this term.EPA believes the language on theimportance of disinfectants is adequatein the rule and thus has not changedthis language. EPA does not agree that

the potential health effects from short-term exposure to elevated levels ofdisinfectants can be dismissed. Ozonedoes not require an MRDLG because itreacts so completely that it does notoccur in water delivered to consumers.Finally, EPA believes the use of theMRDLGs for other disinfectants oroxidants would not be appropriate sinceMRDLGs are developed for regulatedcompounds controlled by MRDLs ortreatment techniques and EPA does notallow these compounds to be used todemonstrate compliance withdisinfection requirements.

The information EPA relied on toestablish the MCLGs and MRDLGs wasdescribed in the 1994 proposal (EPA,1994a), the 1997 DBP NODA (EPA,1997b), and the 1998 NODA (EPA,1998a). Criteria and assessmentdocuments to support the MCLGs andMRDLGs are included in the docket(EPA, 1993a; EPA, 1994 d–h; EPA,1997c; EPA, 1998 b–f; and EPA, 1998p).A summary of the occurrence andexposure information for this rule aredetailed in ‘‘Occurrence Assessment forDisinfectants and DisinfectionByproducts in Public Drinking WaterSupplies’ (EPA, 1998u). The discussionof the data used to establish the MCLGsand MRDLGs and a summary of themajor public comments for thesechemicals are included below. A moredetailed discussion is included belowfor chloroform, DCA, chlorite, chloridedioxide, and bromate than the otherdisinfectants and DBPs. This is the casebecause significant new data hasbecome available since the 1994proposal for these four DBPs and onedisinfectant.

1. MCLG for Chloroforma. Today’s Rule. After careful

consideration of all public comments,EPA has concluded at this time topromulgate an MCLG for chloroform ofzero as proposed. This conclusionreflects an interim risk-managementdecision on the part of the Agency. TheAgency recognizes the strength of thescience in support of a non-linearapproach for estimating carcinogenicityof chloroform. EPA received publiccomments that questioned theunderlying basis and approach used toreach the science judgment that themode of chloroform’s carcinogenicaction supports a nonlinear approach.Equally important are the policy andregulatory issues raised by stakeholdersthat touch on this issue. EPA believesthat it is essential to pursue a furtherdialogue with stakeholders on the issuesraised in the public comments beforeapplying the substantial new data andscience on the mode of carcinogenic


action discussed in the 1998 NODA tothe important decision of moving to anon-linear cancer extrapolationapproach for drinking watercontaminants under the SDWA.Moreover, EPA will complete additionaldeliberations with the Agency’s ScienceAdvisory Board (SAB) (open tostakeholder presentations to the SAB)on the analytical approach used toevaluate and reach conclusions on modeof action data, and the science basis forthe mode of carcinogenic action forchloroform.

In evaluating how to proceed in thedevelopment of an MCLG forchloroform, the Agency believes twoadditional factors must be taken intoconsideration. First, as part of the 1996SDWA amendments, Congressmandated that the Stage 1 DBPR rule bepromulgated by November 1998. EPAhas concluded that it would beimpossible to complete the additionaldeliberations noted above in time tomeet this statutory deadline. Second, asexplained below, the Agency has alsocompleted analysis indicating thatregardless of whether the MCLG isbased on a low-dose linear or non-linearextrapolation approach, the MCLenforceable standard for TTHMs of 0.08mg/L will not be affected. In light ofthese issues, EPA believes it isappropriate and consistent with thepublic health goals of the SDWA toestablish a zero MCLG for chloroformbased on a linear default extrapolationapproach until the Agency is able tocomplete additional deliberations withthe Agency’s SAB on the analyticalapproach used to evaluate and reachconclusions on mode of action data andthe science basis for the mode ofcarcinogenic action for chloroform, andcomplete the process of further publicdialogue on the important question ofmoving to a non-linear cancerextrapolation approach. EPA also notesthat its approach is consistent withlegislative history of the SDWA (see 56FR 3533—EPA, 1991) and the 1996SDWA Amendments.

b. Background and Analysis. As partof its 1994 Stage 1 DBP proposal (EPA,1994a), EPA requested comment on azero MCLG for chloroform. This wasconsistent with information provided tothe 1992 Reg. Neg. Committee and wasbased on data from a drinking waterstudy by Jorgensen et al. (1985)indicating an increase of kidney tumorsin male rats in a dose-related manner.However, at the time of the proposalthere was insufficient data to determinethe mode of carcinogenic action forchloroform. Therefore, EPA based its

1994 proposal on a risk managementdecision that a presumptive or low-doselinear default (i.e, MCLG of zero) wasappropriate until more research becameavailable and there was an adequateopportunity to work with stakeholdersand the scientific community toevaluate and assess the technical as wellas policy and regulatory implications ofsuch new information. The 1994proposal also reflected the Agency’s1986 Guidelines for Carcinogen RiskAssessment (EPA, 1986) whichrecommended reliance on the defaultassumption of low-dose linearity in theabsence of substantial information onthe mechanism of carcinogenicity.

Since the 1994 proposal, over 30toxicological studies have beenpublished on chloroform. These studieswere discussed in the November 1997Stage 1 DBP NODA (EPA, 1997b). Inaddition, EPA published a second DBPNODA in March 1998 (EPA, 1998a)which discussed recommendations andfindings from a 1997 International LifeSciences Institute project (ILSI, 1997),co-sponsored by EPA, on the cancerassessment for chloroform. The ILSIproject included the analysis andconclusions from an expert panel whichwas convened and charged withreviewing the available databaserelevant to the carcinogenicity ofchloroform, and considering how endpoints related to mode of action can beapplied in hazard and dose-responseassessment by using guidance providedby the EPA’s 1996 Proposed Guidelinesfor Carcinogen Assessment (EPA,1996b). The panel was made up of 10internationally recognized scientistsfrom academia, industry, government,and the private sector. Based on aconsideration of the ILSI panel findingsand an assessment of new data onchloroform since 1994, EPA requestedcomment in the 1998 NODA on theAgency’s science conclusion thatchloroform is a likely human carcinogenand that available scientific analysissupports a non-linear mode of action forestimating the carcinogenic riskassociated with lifetime exposure fromingesting drinking water.

As part of the 1998 NODA, EPA alsorequested comment on a revisedchloroform MCLG of 0.30 mg/L. Therevised MCLG was premised on thesubstantial new science noted abovethat supports a non-linear mode ofaction. In calculating the specificMCLG, EPA relied upon data relating tohepatoxicity in dogs (EPA, 1994a). Thishepatoxicity endpoint was deemedappropriate given that hepatic injury isthe primary effect following chloroform

exposure; and that an MCLG based onprotection against liver toxicity shouldbe protective against carcinogenicitygiven that the putative mode of actionunderstanding for chloroform involvescytotoxicity as a key event precedingtumor development. The MCLG of 0.3mg/L was calculated using a relativesource contribution (RSC) of 80 percent.The RSC of 80 percent was based on theassumption that most exposure tochloroform is likely to come fromingestion of drinking water. The 80percent assumption for the RSC wasconsistent with the calculations used toderive the MCLGs for D/DBPs in the1994 proposal. Based on informationreceived during the public commentperiod for the 1998 NODA, EPA isconsidering revising its estimate of theRSC for chloroform as discussed below.

Since the 1998 NODA, EPA hasreevaluated elements of the analysisunderlying a revised MCLG of 0.30 mg/L. Considering recent information notfully analyzed as part of the 1998NODA, the Agency is consideringrevising the assumption of an 80% RSCfrom ingestion of drinking water in viewof data which indicates that exposure tochloroform via inhalation and dermalexposure may potentially contribute asubstantial percentage of the overallexposure to chloroform depending onthe activity patterns of individuals.Also, EPA is in the process ofdeveloping a policy for incorporatinginhalation and dermal exposure into thederivation of the RSC. Furthermore,there is considerable uncertaintyregarding the potential exposure tochloroform via the dietary route andthere is information which indicatesindividuals who are frequent swimmersmay receive a large amount ofchloroform during swimming. There areadditional uncertainties regarding otherpossible highly exposed sub-populations, e.g., from use ofhumidifiers, hot-tubs, and outdoormisters. In conclusion, because theremay be a potential for exposure tochloroform from other routes ofexposure than ingestion of drinkingwater, EPA is considering using the 20percent default floor to ensure adequatepublic health protection. The 20 percenthas been used historically for drinkingwater contaminants other than D/DBPswhen there is uncertainty in theavailable exposure data. The use of the20 percent RSC for chloroform wouldproduce a MCLG of 0.07 mg/L:


MCLG for chloroform =0.01 mg/kg/d 70 kg 0.2

2L/d mg

× × = 0 07. /L

In addition to its reassessment oftechnical assumptions underlying therevised MCLG, the Agency has alsoreviewed and carefully considered indetail a number of significant commentson the 1998 NODA. These commentsreflect both substantial scientificsupport as well as significant concernswith a possible MCLG of 0.30 mg/L. Asoutlined in more detail below, a numberof nationally recognized scientificexperts strongly affirmed the data andtechnical rationale for relying upon anon-linear mode of action forchloroform. Other commenters,however, highlighted several scientificissues they felt were not adequatelyconsidered. These commenters alsoemphasized their concern that thepolicy, regulatory, and enforcementimplications related to a revised MCLGwere not raised by EPA in either the1992 or the 1997 regulatory negotiationprocesses leading up to today’s finalrule. Thus, these commenters felt that anumber of stakeholders whorecommended support for componentsof the Stage 1 DBPR rule did so underone set of conditions and assumptionsthat the Agency subsequently changedwithout providing a sufficientopportunity for further debate anddiscussion.

EPA believes that an adequateopportunity for notice and commentwas provided as a result of the 1997 and1998 DBP NODAs on the underlyingscientific data and technical issue ofmoving to a non-linear extrapolationapproach based on an understanding ofthe mode of carcinogenic action forchloroform and recalculating thechloroform MCLG to a nonzero number.However, the Agency recognizes thatreliance on a non-linear mode of actionunder the SDWA does represent asignificant and precedential, albeitsound, application of new science to thepolicy development and riskmanagement decision making process ofestablishing appropriately protectiveMCLGs. The Agency also recognizesthat although, as discussed below, arevised MCLG for chloroform would notaffect the TTHM MCL under today’srule, the precedential decision to utilizea non-linear cancer extrapolationapproach clearly has importantimplications for the development offuture MCLGs where there is alsoadequate scientific research and data tosupport such a non-linear analysis.

In reviewing the range of scientific,policy, and regulatory analyses and

strongly held views associated withdevelopment of the chloroform MCLG,EPA notes that the one question notfundamentally at issue is theestablishment of the 0.080 mg/L TTHMMCL. The majority of commenters whoaddressed the proposed TTHM MCLcontinue to support it. This isparticularly important to EPA in light ofcongressional action with regard to theM–DBP process in the 1996 SDWAAmendments. In enacting theAmendments and particularly inexpressing congressional intent in theconference Report, Congress was carefulto emphasize ‘‘that the new provisionsof this conference agreement notconflict with the parties’ agreement nordisrupt the implementation of theregulatory actions,’’ (such as the currentagreement on an TTHM MCL of 0.080mg/L). Both of these important elementsof the Congressional intent werereflected in the statutory text. Section1412(b)(2)(C) requires EPA to maintainthe M–DBP rule staggered promulgationstrategy agreed to by the negotiatedrulemaking; and Section 1412(b)(6)(C)exempted the future M–DBP rules fromthe new cost-benefit standard-settingprovision (1412(b)(6)(A)) but not fromthe new risk-risk provision (1412(b)(5)),because the latter was a part of thenegotiated rulemaking agreement butthe former was not.

The Agency, itself, also believes thatthe underlying logic, data, and rationalesupporting establishment of a TTHM of0.080 mg/L MCL is compelling, and thisis a critical factor in the Agency’schloroform MCLG decision undertoday’s rule. Under either a low-doselinear or non-linear extrapolation toderive the MCLG, the final TTHM MCLremains unaffected.

After thorough review of the data andcomments, EPA believes the nonlinearcancer extrapolation approach is themost appropriate means to establish anMCLG for chloroform based oncarcinogenic risk. However, in light ofits own reconsideration of theappropriate RSC for chloroform undersuch an approach, considering the rangeof policy, regulatory, and enforcementissues raised as part of the publiccomment period, recognizing theimportance of deliberations with SABbefore proceeding further and, yet,recognizing that this cannot beaccomplished within the constraints ofmeeting the statutory deadline for Stage1 DBPR rule of November 1998, EPA hasdetermined that on balance the more

appropriate and prudent riskmanagement decision at this time is toestablish an MCLG for chloroform at theproposed presumptive default level ofzero. As part of this decision, theAgency will complete additionaldeliberations with the Agency’s SAB onthe analytical approach used to evaluateand reach conclusions on mode ofaction data, and the science basis for themode of carcinogenic action forchloroform. The SAB’s review will befactored into the Agency’s Stage 2 DBPrulemaking process. EPA will alsoinclude consideration of the regulatory,policy, and precedential issuesinvolving chloroform in the Agency’sRound 2 M–BP stakeholder process.EPA wishes to make clear that itsinterim decision in today’s rule to set anMCLG of zero pending SAB review andfurther stakeholder involvement is notintended to prejudge the question ofwhat the appropriate MCLG should befor purposes of regulatory decisionsunder the Stage 2 DBPR. EPA maydecide to retain the zero MCLG for thatrule, or to revise it, depending on theoutcome of the SAB review, as well asany new scientific evidence that maybecome available. In regard to theappropriate RSC factor, in case a non-linear approach should ultimately beadopted, the Agency requests thatstakeholders provide any data they manhave bearing on this determination.

The fundamental objective of theSDWA is to establish protective publichealth goals (MCLGs) together withenforceable standards (MCLs ortreatment techniques) to move the watertreatment systems as close to the publichealth goal as is technologically andeconomically feasible. In the case of thechloroform and TTHMs, this objective ismet with whichever extrapolationapproach (low dose linear versusnonlinear) is relied upon.

c. Summary of Comments. EPAreceived numerous comments on boththe 1994 proposed rule regarding theMCLG of zero for chloroform and theMCLG of 0.3 mg/L contained in the1998 NODA. Some commenters weresupportive of the MCLG of zero, whileothers were supportive of the 0.3 mg/LMCLG. The major reason raised bycommenters for establishing a nonzeroMCLG (e.g., 0.3 mg/L) was that therewas convincing scientific evidence toconclude that a nonlinear margin ofexposure approach for evaluating thecarcinogenic risk from chloroform iswarranted. Commenters who were


against establishing a nonzero MCLG forchloroform presented policy andscientific concerns. Scientific concernsraised by commenters opposed to thenonzero MCLG included theirperceptions that: there is insufficientscientific evidence of a threshold forchloroform; the threshold assumption isalso invalid because chloroform co-occurs with other mutageniccarcinogens; EPA ignored human datain establishing the MCLG forchloroform; the linkage betweencytotoxicity and regenerativeproliferation and kidney tumors is notsupported by the data; and the evidencefor genotoxicity is mixed and it wouldbe difficult if not impossible toconclude that the evidence demonstratechloroform has no direct effect on DNA.As detailed at greater length in thedocket, EPA does not agree with thesecomments as a technical matter. TheAgency does agree with the commentersview that further discussion of theseissues with both the SAB and as part ofadditional public dialogue isappropriate.

The policy issues raised bycommenters included their belief that: azero MCLG is required to comply withprovisions of the SDWA; EPA isrequired to use the 1986 CancerGuidelines (EPA, 1986) until the 1996Cancer Guidelines (EPA, 1996b) areformally finalized, and under the 1986guidelines the MCLG for chloroformmust be set at zero; EPA did not providesufficient opportunity for the membersof the FACA, established to assist in thedevelopment of the Stage 1 DBP rule, toproperly consider the potentialimplications of a nonzero MCLG; andsetting a MCLG for chloroform (0.3 mg/L) above the MCL for the TTHMs (0.08mg/L) is illogical.

In response, EPA believes that theunderlying science for using a nonlinearextrapolation approach to evaluate thecarcinogenic risk from chloroform iswell founded. As explained above,because of the issues raised during thepublic comment period, EPA believesadditional review and dialogue withstakeholders is needed prior todeparting from a long-held EPA policyof establishing zero MCLGs for knownor probable carcinogens. EPA will alsocomplete additional deliberations withthe Agency’s SAB on the analyticalapproach used to evaluate and reachconclusions on mode of action data, andthe science basis for the mode ofcarcinogenic action for chloroform.

In response to the policy issues raisedby commenters, EPA, historically, hasestablished MCLGs of zero for known orprobable human carcinogens based onthe principle that any exposure to

carcinogens might represent some finitelevel of risk and therefore an MCLGabove zero did not meet the statutoryrequirement that the goal be set whereno known anticipated adverse effectsoccur, allowing for an adequate marginof safety (56 FR 3533; EPA, 1991).However, if there is scientific evidencethat indicates there is a ‘‘safe threshold’’then a non-zero MCLG could beestablished with an adequate margin ofsafety (56 FR 3533; EPA, 1991)). Eventhough EPA, as an interim matter, isestablishing an MCLG of zero forchloroform in today’s rule, it believes ithas the authority to establish nonzeroMCLGs for carcinogens if the scientificevidence supports this finding.

In response to commenter’s concernswith EPA using the proposed 1996Guidelines for Carcinogen RiskAssessment (EPA, 1996b) instead of theAgency’s 1986 guidelines, EPA believesit is important to point out that the 1986guidelines provide for departures fromdefault assumptions such as low doselinear assessment. For example, the1986 EPA guidelines reflect the positionof the OSTP (1985; Principle 26) ‘‘Nosingle mathematical procedure isrecognized as the most appropriate forlow-dose extrapolation incarcinogenesis. When relevantbiological evidence on mechanisms ofaction exists (e.g, pharmacokinetics,target organ dose), the models orprocedure employed should beconsistent with the evidence.’’ The 1986guideline goes on to further state ‘‘TheAgency will review each assessment asto the evidence on carcinogenesismechanisms and other biological orstatistical evidence that indicates thesuitability of a particular extrapolationmodel.’’ The EPA’s 1996 ProposedGuidelines for Carcinogen RiskAssessment allow EPA to use otherdefault approaches to estimate cancerrisk than the historic, linearizedmultistage default when there is anunderstanding of an agent’s mode ofcarcinogenic action. EPA believes thatreliance on the 1986 guidance allowsEPA to reach the same conclusion onthe carcinogenic risk from chloroform asif the 1996 guidelines were used. Theuse of the best available science is a coreEPA principle and is statutorilymandated by the SDWA amendments of1996. The 1996 Proposed Guidelines forCarcinogen Risk Assessment reflect newscience and are consistent with theexisting 1986 Guidelines for CarcinogenRisk Assessment. EPA considered the1996 proposed guidelines in assessingthe health effects data for chloroformand the other contaminants discussed inthe 1998 March NODA.

EPA agrees with commenters thatadditional review by the FACA of theregulatory implications of a nonlinearapproach is appropriate for policyreasons, and will initiate thesediscussions in the context of the Stage2 DBPR FACA deliberations. In light ofthe November 1998 statutory deadlineto promulgate the Stage 1 DBP rule andthe steps necessary to complete a finalrule, EPA has concluded that there isnot enough time to meet with the SABand FACA, provide ample opportunityfor debate, resolve differing points ofviews, and complete additional analysisto meet stakeholders policy concerns inthe context of the Stage 1 DBP rule. EPAnotes, however, that regardless of theMCLG for chloroform, the MCL for theTHMs remains at 0.08 mg/L. Since theMCL is the enforceable standard thatwater systems will be required to meet,a nonlinear or low dose linearextrapolation to derive the MCLG willnot have a direct impact on thecompliance obligations of public watersystems or on the levels of chloroformallowed in public water systems,although it may be relevant todevelopment of enforceable regulatorylimits established under future rules.

2. MCLG for Bromodichloromethane(BDCM)

a. Today’s Rule. The final MCLG forBDCM is zero. The zero MCLG is basedon the classification of BDCM as aprobable human carcinogen. The MCLGwas determined in a weight-of-evidenceevaluation which considered allrelevant health data includingcarcinogenicity and reproductive anddevelopmental toxicity animal data.EPA believes the data are insufficient atthis time to determine the mode ofcarcinogenic action for BDCM, andtherefore a low dose linear extrapolationapproach is used to estimate lifetimecancer risk as a default.

b. Background and Analysis. In the1994 Stage 1 DBPR proposal, the MCLGof zero for BDCM was based on largeintestine and kidney tumor data from aNational Toxicology Program (NTP)chronic animal study (NTP, 1987). Sincethe proposal, several new studies havebeen published on BDCM metabolism(EPA, 1997c). In addition, several newgenotoxicity studies and short-termtoxicity studies including reproductiveevaluations were found for BDCM (EPA,1997c). These new studies contribute tothe weight-of-evidence conclusionsreached in the 1994 proposal. Based onthis evidence, the final MCLG for BDCMis zero based on sufficient evidence ofcarcinogenicity in animals.

c. Summary of Comments. Severalcommenters disagreed with the use of a


corn oil gavage animal cancer study todetermine the MCLG for BDCM. Somecommenters agreed with the EPAdecision to use large intestine andkidney tumor data from the corn oilgavage study, but not liver tumor datain the quantitative estimation ofcarcinogenic risk. One commenteragreed that a low-dose linearextrapolation approach to dose-responseassessment was appropriate at this timeand consistent with EPA policy.However, this commenter suggested thatEPA undertake chronic studies thatinclude a drinking water study of BDCMand toxicokinetics. One commenterdisagreed with the EPA conclusion thatthe evidence on the mutagenicity ofBDCM is adequate.

In response, EPA agrees withcommenters that a drinking water studyis preferable to a corn oil gavage studyto assess risk from DBPs in drinkingwater. However, the NTP corn oilgavage study is the best data availableon BDCM for a quantitative riskestimation at this time. BDCM iscurrently being tested for toxicokineticsand cancer in a chronic BDCM drinkingwater rodent study by the NTP. Whenthese data are available, EPA willreassess the cancer risk of BDCM. EPAbelieves that the animal data currentlyavailable on BDCM are consistent withEPA cancer guidelines on classifyingBDCM as a probable human carcinogengiven the evidence on mutagenicity andgiven there was an increased incidenceof tumors at several sites in the animals.Additionally, tumors were found inboth sexes of two rodent species.Finally, there have been several newstudies on the genotoxicity of BDCMthat have supported a mutagenicpotential for BDCM (EPA, 1997c)

3. MCLG for Dibromochloromethane(DBCM)

a. Today’s Rule. The final MCLG forDBCM is 0.06 mg/L. This MCLG isbased on a weight of evidenceevaluation of the cancer and noncancerdata which resulted in the classificationof DBCM as a possible humancarcinogen.

b. Background and Analysis. In the1994 proposal, the MCLG of 0.06 mg/Lfor DBCM was based on observed livertoxicity from a subchronic study andpossible carcinogenicity (NTP, 1985).EPA is not aware of any newinformation that would change itsevaluation of DBCM since the proposal.The final MCLG is therefore 0.06 mg/L.

c. Summary of Comments. Severalcommenters disagreed with theadditional safety factor of 10 to accountfor possible carcinogenicity that wasused in the MCLG calculation. One

commenter agreed with EPA’s decisionto base the MCLG on noncarcinogenicendpoints. Several commentersdisagreed with the use of a corn oilgavage study to determine the MCLG forDBCM.

In response, because the evidence ofcarcinogenicity was limited on DBCM(i.e., increased tumor response in onlyone of the two species tested), EPAclassified DBCM as a possible humancarcinogen. The additional factor of 10to account for possible carcinogenicityfollows EPA’s science policy forestablishing MCLGs (EPA, 1994a). EPAused liver effects from the NTPsubchronic corn oil gavage study as thebasis for the Reference Dose (RfD). EPAagrees with the comment that this is anappropriate basis for deriving the RfDfor DBCM. EPA agrees with commentersthat a drinking water study is preferableto a corn oil gavage study to assess riskfrom DBPs in drinking water. However,the NTP corn oil gavage study is the bestdata available on DBCM for derivationof the MCLG at this time. EPA does notplan to conduct additional chronicstudies for DBCM but is conductingadditional toxicokinetics and short termdrinking water studies on DBCM tobetter understand the potential riskassociated with exposure throughdrinking water.

4. MCLG for Bromoforma. Today’s Rule. The final MCLG for

bromoform is zero. The zero MCLG isbased on a weight-of-evidenceclassification that bromoform is aprobable human carcinogen based on aconsideration of all relevant health dataincluding cancer and noncancer effects.EPA believes the data are insufficient atthis time to determine the mode ofcarcinogenic action for bromoform, andtherefore a low dose linear extrapolationapproach is used to estimate lifetimecancer risk as a default.

b. Background and Analysis. Theproposed MCLG for bromoform waszero. This MCLG was based on an NTPchronic animal carcinogenicity study(NTP, 1989). Since the proposal, newstudies on the genotoxicity ofbromoform were found. However, thesenew studies do not support changingthe proposed MCLG of zero forbromoform. The final MCLG forbromoform is therefore zero.

c. Summary of Comments. Severalcommenters agreed with EPA’sclassification for bromoform as aprobable carcinogen. Other commentersdisagreed with this classification statingthat there was insufficient evidenceavailable because tumors were found inonly one species and the increasednumber of tumors was small. These

commenters generally felt that EPAshould use an RfD approach inquantifying the risk for bromoform.Some commenters encouraged EPA toconduct more experiments onbromoform toxicity. Some commenterswere concerned with the use of a cornoil gavage study to determinecarcinogenic risk.

In response, although the increase intumors was small, the increase wasconsidered significant because largeintestine tumors in both male andfemale rats are rare and thus providessufficient evidence to classifybromoform as a probable humancarcinogen. EPA does not plan onconducting additional chronic testingfor bromoform at this time, but isconducting toxicokinetic studies andshorter term drinking water studies tobetter understand the potential riskassociated with exposure to bromoformin drinking water. EPA agrees withcommenters that drinking water studiesare preferable to a corn oil gavage studyto assess risk from DBPs in drinkingwater. However, the NTP corn oilgavage study is the best data availableon bromoform for derivation of theMCLG.

5. MCLG for Dichloroacetic Acid (DCA)a. Today’s Rule. The final MCLG for

DCA is zero. EPA has developed aweight-of-evidence characterization forDCA in which it evaluated all relevanthealth data (both cancer and noncancereffects). The MCLG of zero is based onsufficient evidence of carcinogenicity inanimals which indicates that DCA is aprobable human carcinogen (likelyunder proposed cancer guidelines). EPAbelieves the data are insufficient at thistime to determine the mode ofcarcinogenic action for DCA and thatthe data is insufficient to quantify thepotential cancer risk from DCA.

b. Background and Analysis. EPAproposed an MCLG of zero for DCA.This was based on classifying DCA as aprobable human carcinogen inaccordance with the 1986 EPAGuidelines for Carcinogen RiskAssessment (EPA, 1986). The DCAcategorization was based primarily onfindings of liver tumors in rats andmice, which was regarded as‘‘sufficient’’ evidence in animals. Nolifetime risk calculation was conductedat the time of the proposal because therewas insufficient data to quantify the risk(EPA, 1994a).

As pointed out in the 1997 and 1998DBP NODAs, several toxicologicalstudies have been identified for DCAsince the 1994 proposal (EPA, 1997c). Inaddition, EPA co-sponsored an ILSIproject in which an expert panel was


convened to explore the application ofthe EPA’s 1996 Proposed Guidelines forCarcinogen Risk Assessment (EPA,1996b) to the available data on thepotential carcinogenicity of chloroformand DCA. The panel considered data onDCA which included chronic rodentbioassay data and information onmutagenicity, tissue toxicity,toxicokinetics, and other mode of actioninformation. The panel concluded thatthe potential human carcinogenicity ofDCA ‘‘cannot be determined’’ primarilybecause of the lack of adequate rodentbioassay data (ILSI, 1997).

EPA prepared a new hazardcharacterization regarding the potentialcarcinogenicity of DCA in humans(EPA, 1998b). One objective of thisreport was to develop a weight-of-evidence characterization using theprinciples of the EPA’s 1996 ProposedGuidelines for Carcinogen RiskAssessment (EPA, 1996b) which areconsistent with the 1986 Guidelines.Another objective of the report was toconsider new data since the 1994proposal and to address the issuesraised by the 1997 ILSI panel report.

EPA agreed with the ILSI panel reportthat the mode of action through whichDCA induces liver tumors in both ratsand mice cannot be reasonablydetermined at this time. EPA disagreeswith the ILSI panel that the potentialhuman carcinogenicity cannot bedetermined. Based on thehepatocarcinogenic effects of DCA inboth rats and mice in multiple studies,as well as other date, for example,showing that DCA alters cell replicationand gene expression, EPA concludesthat DCA should be considered as a‘‘likely’’ (probable) cancer hazard tohumans (EPA, 1998b). Therefore, as inthe 1994 proposed rule, EPA believesthat the MCLG for DCA should remainzero to assure public health protection.

c. Summary of Comments. Somecommenters agreed with the zero MCLGfor DCA based on positive carcinogenicfindings in two animal species. Severalcommenters stated that a zero MCLGwas inappropriate due to evidencewhich indicates a nongenotoxic mode ofaction for DCA. The comment wasraised that the animal evidence wasinsufficient to consider DCA a likely(probable) human carcinogen, and thatDCA should be considered at mostsuggestive of carcinogenicity.

In response, EPA concludes that DCAshould be considered as a probable(likely under the 1996 proposedguidelines) cancer hazard to humans(EPA, 1998b) based on thehepatocarcinogenic effects of DCA inboth rats and mice in multiple studies,and mode of action related effects (e.g.,

mutational spectra in oncogenes,elevated serum glucocorticoid levels,alterations in cell replication anddeath). EPA considers the mode ofaction through which DCA induces livertumors in both rats and mice to beunclear, and thus the likelihood ofhuman hazard associated with lowlevels of DCA usually encountered inthe environment or in drinking water isnot sufficiently understood. EPAacknowledges that a mutagenicmechanism (i.e., direct DNA reactivity)may not be an important influence onthe carcinogenic process at low doses.EPA believes that the lack ofmutagenicity is not a sufficient basis todepart from a low dose linear defaultextrapolation approach for the cancerassessment. There must be otherconvincing evidence to explain how thetumors are caused by the chemical. Thecommenters have not presented suchevidence. Although DCA tumor effectsare associated with high doses used inthe rodent bioassays, there isuncertainty regarding whether the modeof tumorgenesis is solely throughmechanisms that are operative only athigh doses. Therefore, as in the 1994proposed rule, EPA believes that theMCLG for DCA should remain as zero toassure public health protection. NTP isimplementing a new two year rodentbioassay that will include fullhistopathology at lower doses thanthose previously studied. Additionally,studies on the mode of carcinogenicaction are being done by variousinvestigators including the EPA healthresearch laboratory.

6. MCLG for Trichloroacetic Acid (TCA)a. Today’s Rule. The final MCLG for

TCA is 0.3 mg/L, as was proposed in1994. This MCLG is based ondevelopmental toxicity and limitedevidence of carcinogenicity in animals.

b. Background and Analysis. The1994 proposed rule included a MCLG of0.3 mg/L for TCA based ondevelopmental toxicity and possiblecarcinogenicity based on limitedevidence in animal studies (i.e.,hepatocarcinogenicity in mice). Sincethe proposal, a 2-year carcinogenicitystudy on TCA (DeAngelo et al., 1997)found that TCA was not carcinogenic inmale rats. As was discussed in the 1997DBP NODA (EPA, 1997b), there havealso been several recent studiesexamining the mode of carcinogenicaction for TCA. These new studiessuggest that TCA does not operate viamutagenic mechanisms. For a more indepth discussion of this new data referto the 1997 DBP NODA (EPA, 1997b)and related support documents (EPA,1997c). This new information does not

alter the original assessment of thehealth effects of TCA based ondevelopmental toxicity and limitedevidence of carcinogenicity. Therefore,the MCLG will remain 0.3 mg/L.

c. Summary of Comments. Severalcommenters agreed with theclassification of TCA as a possiblehuman carcinogen. One commenter feltthat toxicity data on TCA indicated athreshold. Some commenters disagreedwith the study selected for estimatingthe RfD (Smith et al. 1989). Somecommenters stated the uncertaintyfactors used to establish the RfD weretoo high.

In response, EPA acknowledges that aDNA reactive mutagenic mechanismmay not be involved in TCA’s mode ofcarcinogenicity. Because an RfD wasused in lieu of a quantitative cancerassessment for establishing the MCLG,however, there was no need to evaluatethe mode of carcinogenic action for TCAat this time. EPA believes that the Smithet al. (1989) study is appropriate to usein quantifying risk from TCA sincedevelopmental toxicity was the mostcritical effect. EPA believes that anuncertainty factor of 3,000 isappropriate to account for inter andintraspecies differences (100), a lowestobserved adverse effects level (LOAEL)(10), and lack of a two-generationreproductive study (3) (EPA, 1994a).These uncertainty factors are consistentwith current Agency science policy onusing uncertainty factors (EPA, 1994a).

7. MCLG for Chlorite and MRDLG forChlorine Dioxide

a. Today’s Rule. The final MCLG forchlorite is 0.8 mg/L and the finalMRDLG for chlorine dioxide is 0.8 mg/L. The MCLG for chlorite was increasedfrom the proposed value of 0.08 mg/L to0.8 mg/L based on a weight-of-evidenceevaluation of all health data on chloriteincluding a recent two-generationreproductive rat study sponsored by theChemical Manufactures Association(CMA, 1996). The MRDLG for chlorinedioxide was increased from theproposed value of 0.3 mg/L to 0.8 mg/L based on a weight-of-evidenceevaluation using all the health data onchlorine dioxide including theinformation on chlorite from the CMAstudy. EPA believes that data on chloriteare relevant to assessing the risks ofchlorine dioxide because chlorinedioxide is rapidly reduced to chlorite.Therefore, the findings from the CMAstudy and previously described studiesin the 1994 proposal were used to assessthe risk for both chlorite and chlorinedioxide.

b. Background and Analysis. The1994 proposal included an MCLG of


0.08 mg/L for chlorite. The proposedMCLG was based on an RfD of 3 mg/kg/d estimated from a lowest-observed-adverse-effect-level (LOAEL) forneurodevelopmental effects identifiedin a rat study by Mobley et al. (1990).This determination was based on aweight of evidence evaluation of all theavailable data at that time (EPA, 1994d).An uncertainty factor of 1000 was usedto account for inter-and intra-speciesdifferences in response to toxicity (afactor of 100) and to account for use ofa LOAEL (a factor of 10).

The 1994 proposal included anMRDLG of 0.3 mg/L for chlorinedioxide. The proposed MRDLG wasbased on a RfD of 3 mg/kg/d estimatedfrom a no-observed-adverse-effect-level(NOAEL) for developmentalneurotoxicity identified from a rat study(Orme et al., 1985; EPA, 1994d). Thisdetermination was based on a weight ofevidence evaluation of all availablehealth data at that time (EPA, 1994a).An uncertainty factor of 300 wasapplied that was composed of a factorof 100 to account for inter-and intra-species differences in response totoxicity and a factor of 3 for lack of atwo-generation reproductive studynecessary to evaluate potential toxicityassociated with lifetime exposure. Tofill this important data gap, the CMAsponsored a two-generationreproductive study in rats (CMA, 1996).

As described in more detail in the1998 NODA (EPA, 1998a), EPAreviewed the CMA study and completedan external peer review of the study(EPA, 1997d). In addition, EPAreassessed the noncancer health risk forchlorite and chlorine dioxideconsidering the new CMA study (EPA,1998d). This reassessment was also peerreviewed (EPA, 1998d). Based on thisreassessment, EPA requested commentin the 1998 NODA (EPA, 1998a) onchanging the proposed MCLG forchlorite from 0.08 mg/L to 0.8 mg/Lbased on the NOAEL identified from thenew CMA study which reinforced theconcern for neurodevelopmental effectsassociated with short-term exposures.

EPA determined that the NOAEL forchlorite should be 35 ppm (3 mg/kg/dchlorite ion, rounded) based on aweight-of-evidence approach. The dataconsidered to support the NOAEL aresummarized in EPA (1998d) andincluded the CMA study as well asprevious reports on developmentalneurotoxicity and other adverse healtheffects (EPA, 1998d). EPA continues tobelieve, as stated in the 1998 NODA(EPA, 1998a), that the RfD for chloriteshould be 0.03 mg/kg/d (NOAEL of 3mg/kg/d with an uncertainty factor of100) and that a MCLG of 0.8 mg/L is

appropriate. EPA has concluded that theRfD for chlorine dioxide should be 0.03mg/L (NOAEL of 3 mg/kg/d with anuncertainty factor of 100) and that aMRDLG of 0.8 mg/L is appropriate.

c. Summary of Comments. EPAreceived numerous comments on the1994 proposal (EPA, 1994a) and 1998NODA (EPA, 1998a). The majorcomment from the 1994 proposal wasthat reliance on the Mobley et al. (1990)study for the MCLG for chlorite and theOrme et al. (1985) study for chlorinedioxide were inappropriate and that theresults from the CMA study must beevaluated before any conclusions on theMCLG for chlorite or chlorine dioxidecould be drawn. In relation to the 1998NODA, several commenters supportedchanging the MCLG for chlorite andMRDLG for chlorine dioxide whileothers were concerned that the sciencedid not warrant a change in thesevalues. The major comments submittedagainst raising the MCLG and MRDLGfocused on several issues. First, onecommenter argued that the 1000-folduncertainty factor used for chlorite inthe proposal should remain in placebecause the CMA study used to reducethe uncertainty factor was flawed.Second, several commenters indicatedthat the LOAEL should be set at thelowest dose level (35 ppm) becausecertain effects at the lowest dose testedmay have been missed. Finally, somecommenters argued that an additionalsafety factor should be included toprotect children and drinking waterconsumption relative to the body weightof children should be used instead ofthe default assumption of 2 L per dayand 70 kg adult body weight.

EPA agrees with commenters on the1994 proposal that the results from theCMA should be factored into any finaldecision on the MCLG for chlorite andchlorine dioxide. As explained in moredetail in the 1998 DBP NODA (EPA,1998a), EPA considered the findingsfrom the CMA study along with otheravailable data to reach its conclusionsregarding the MCLG and MRDLG forchlorite and chlorine dioxide.

EPA disagrees with the commenterwho suggested that the 1000-folduncertainty factor for chlorite shouldremain because the CMA study wasflawed. The study design for theneurodevelopmental component of theCMA study was in accordance withEPA’s testing guidelines at the time thestudy was initiated. EPA had previouslyreviewed the study protocol for theCMA neurotoxicity component and hadapproved the approach. While EPAinitially had some questions regardingthe design of the neurodevelopmentalcomponent of the study (Moser, 1997),

subsequent information submitted bythe CMA provided clarification oncertain aspects of the study design(CMA, 1998). EPA agrees that even withthe clarifications that there are somelimitations with theneurodevelopmental component of theCMA study. EPA believes that theneuropathology components of the CMAstudy were adequate. The functionaloperation battery had someshortcomings in that forelimb andhindlimb grip strength and foot splaywere not evaluated. EPA believes theresults from the motor activitycomponent of the CMA study weredifficult to interpret because of the highvariability in controls. However, in itsevaluation of the MCLG for chlorite andchlorine dioxide, EPA did not relysolely on the CMA study, but used aweight-of-evidence approach thatincluded consideration of severalstudies. Thus, the shortcomings of onestudy are offset by the weight from otherstudies. EPA believes that the CMAstudy contributes to the weight-of the-evidence. The studies by Orme et al.(1985), Mobley et al. (1990), and CMA(1996) support a NOAEL of 3 mg/kg/dbased on neurodevelopmental effects(e.g., decreased exploratory, locomotorbehavior, decreased brain weight).Furthermore, the CMA study wasreviewed by outside scientists as well asby EPA scientists. EPA’s re-assessmentfor chlorite and chlorine dioxidepresented in the 1998 March NODA wasreviewed internally and externally inaccordance with EPA peer-reviewpolicy. The three outside experts whoreviewed the Agency’s assessmentagreed with the NOAEL of 3 mg/kg/dayand the derived RfD.

Finally, EPA disagrees that anadditional safety factor should beapplied to provide additional protectionfor children or that drinking waterconsumption relative to the body weightof children should be used indeveloping the MCLG. The MCLG andMRDLG presented for chlorite andchlorine dioxide are considered to beprotective of susceptible groups,including children, given that the RfD isbased on a NOAEL derived fromdevelopmental testing, which includes atwo-generation reproductive study. Atwo-generation reproductive studyevaluates the effects of chemicals on theentire developmental and reproductivelife of the organism. Additionally,current methods for developing RfDs aredesigned to be protective for sensitivepopulations. In the case of chlorite andchlorine dioxide a factor of 10 was usedto account for variability between theaverage human response and the


response of more sensitive individuals.In addition, the important exposure isthat of the pregnant and lactating femaleand the nursing pup. The 2 liter per daywater consumption and the 70 kg bodyweight assumptions are viewed asadequately protective of all groups.

Based on a review of all the data andpublic comments, EPA believes that theMCLG for chlorite should be 0.8 mg/Land the MRDLG for chlorine dioxideshould be 0.8 mg/L. EPA believes theMCLG and MRDLG are consistent withthe discussions during the regulatorynegotiations which recognized the needfor an acceptable two-generationreproductive study prior to reducing the

uncertainty factors for chlorite andchlorine dioxide. EPA believes the CMAprovided an acceptable two-generationstudy with which to reduce theuncertainty factors. In addition, EPAbelieves potential health concerns in theproposal with having a MCLG forchlorite significantly below the MCL areno longer relevant because the MCL forchlorite in today’s rule will remain at1.0 mg/L while the MCLG has beenrevised to 0.8 mg/L. Given the margin ofsafety that is factored into theestimation of the MCLG of 0.8 mg/L,EPA believes that the MCL of 1.0 mg/L will be protective of public health of

all groups, including fetuses andchildren.

The MCLG for chlorite is based on anRfD of 0.03 mg/kg/d using a NOAEL of3 mg/kg/d and an uncertainty factor of100 to account for inter- and intra-species differences. The MCLG forchlorite is calculated to be 0.8 mg/L byassuming an adult tap waterconsumption of 2 L per day for a 70 kgadult and using a relative sourcecontribution of 80% (because mostexposure to chlorite is likely to comefrom ingestion of drinking water—EPA,1998u). A more detailed discussionof this assessment is included in thepublic docket for this rule (EPA, 1998d).

MCLG for chlorite =0.03 mg/kg/d 70 kg 0.8

2L/day mg

MCLG for chlorite = 0.8 mg/L (Rounded)

× × = 0 84. /L

For chlorine dioxide the MCLG isbased on a NOAEL of 3 mg/kg/d andapplying an uncertainty factor of 100 toaccount for inter-and intra-speciesdifferences in response to toxicity, therevised MRDLG for chlorine dioxide is

calculated to be 0.8 mg/L. This MRDLGtakes into account an adult tap waterconsumption of 2 L per day for a 70 kgadult and applies a relative sourcecontribution of 80% (because mostexposure to chlorine dioxide is likely to

come from ingestion of drinking water—EPA, 1998u). A more detaileddiscussion of this assessment isincluded in the public docket for thisrule (EPA, 1998d).

MRDLG for chlorine dioxide =0.03 mg/kg/d 70 kg 0.8

2L/day mg

MRDLG for chlorine dioxide = 0.8 mg/L (Rounded)

× × = 0 84. /L

8. MCLG for Bromatea. Today’s Rule. The final MCLG for

bromate is zero. The zero MCLG isbased on a weight-of-evidenceevaluation of both the cancer andnoncancer effects which indicates thereis sufficient laboratory animal data toconclude that bromate is a probable(likely under the 1996 proposed cancerguidelines) human carcinogen. EPAbelieves the data are insufficient at thistime to determine the mode ofcarcinogenic action for bromate, andtherefore a low dose linear extrapolationapproach is used to estimate lifetimecancer risk as a default.

b. Background and Analysis. The1994 proposed rule included a MCLG ofzero for bromate based on adetermination that bromate was aprobable human carcinogen. Thisdetermination was based on results froma two species rodent bioassay byKurokawa et al. (1986a and 1986b) thatfound kidney tumors in rats. Since the1994 proposed rule, EPA has completedand analyzed a new chronic cancerstudy in male rats and mice forpotassium bromate (DeAngelo et al.,1998). EPA reassessed the cancer risk

associated with bromate exposure (EPA,1998e), had this reassessment peerreviewed (EPA, 1998e), and presentedits findings in the March 1998 NODA(EPA, 1998a). The new rodent cancerstudy by DeAngelo et al. (1998)contributes to the weight of theevidence for the potential humancarcinogenicity of potassium bromateand confirms the study by Kurokawa etal. (1986 a,b).

c. Summary of Comments. Severalcommenters supported the zero MCLGfor bromate. Others believed the MCLGof zero was not justified because thereis evidence of a carcinogenic threshold.This evidence indicates that bromatecauses DNA damage indirectly via lipidperoxidation, which generates oxygenradicals which in turn induce DNAdamage. Other commenters argued thateven if there is no carcinogenicthreshold, EPA has overstated thepotency of bromate by using thelinearized multistage model and shouldinstead use the Gaylor-Kodell model.

In response, EPA disagrees withcommenters who believed that the zeroMCLG was inappropriate. At this time,under the principles of both the 1986

EPA Guidelines for Carcinogen RiskAssessment (EPA, 1986) and the draft1996 EPA Proposed Guidelines forCarcinogen Risk Assessment (EPA,1996b) weight-of-evidence approach,bromate is considered to be a probableor likely human carcinogen. This weightof evidence conclusion of potentialhuman carcinogenicity is based onsufficient experimental findings thatinclude the following: tumors atmultiple sites in rats; tumor responsesin both sexes; and evidence formutagenicity including point mutationsand chromosomal aberrations in in vitrogenotoxicity assays. Furthermore, EPAbelieves there is insufficient evidence atthis time to draw conclusions regardingthe mode of carcinogenic action forbromate. EPA acknowledges there arestudies available showing that bromatemay generate oxygen radicals whichincrease lipid peroxidation and damageDNA. However, no data are availablethat link this proposed mechanism totumor induction. Thus, EPA believesthat while there are studies whichprovide some evidence to support thecommenters’ claims, these studies areinsufficient at this time to establish


lipid peroxidation and free radicalproduction as key events responsible forthe induction of the multiple tumorresponses seen in the bromate rodentbioassays (EPA, 1998e). Given theuncertainty about the mode ofcarcinogenic action for bromate, EPAbelieves it is appropriate to use thedefault assumption of low dose linearityto estimate the cancer risk and establishthe MCLG of zero for bromate. EPA isconducting additional studiesinvestigating the mode of action forbromate.

EPA also disagrees with commenterswho suggested that the Gaylor-Kodellmodel should be used for low-doseextrapolation of the bromate data. In the1998 NODA, a low dose linearextrapolation of the DeAngelo et al.(1998) data was conducted using a one-stage Weibull time-to-tumor model. TheWeibull model was considered to be thepreferred approach to account for thereduction in animals at risk that may bedue to the decreased survival observedin the high dose group toward the endof the study. The estimate of cancer riskfrom the DeAngelo et al. (1998) study issimilar with the risk estimate derivedfrom the Kurokawa et al. (1986a) studypresented in the 1994 proposed rule.

Based on an evaluation of all the dataand after review and consideration ofthe public comments, EPA believes theMCLG for bromate should be zero.

9. MCLG for Chloral Hydratea. Today’s Rule. EPA has decided to

not include an MCLG for chloralhydrate in the Stage 1 DBPR. Thisdecision is based on an analysis of thetechnical comments and on the fact thatchloral hydrate will be controlled by theMCLs for TTHM and HAAs and by thetreatment technique of enhancedcoagulation.

b. Background and Analysis. The1994 proposed rule included an MCLGfor chloral hydrate of 0.04 mg/L. Thiswas based on a 90-day mice study bySanders et al. (1982) which reportedliver toxicity. A RfD of 0.0016 mg/kg/dwas used (LOAEL of 16 mg/kg/d with anuncertainty factor of 10,000). In the1997 DBP NODA (EPA,1997b) andsupporting documents (EPA, 1997c),additional studies on chloral hydratewere discussed, however, these newstudies did not indicate a change in theMCLG for chloral hydrate.

c. Summary of Comments. Themajority of commenters disagreed withthe MCLG of 0.04 mg/L for chloralhydrate. Several commenters questionedthe need for an MCLG for chloralhydrate. These commenters mentionedits low toxic potential and the fact thatsafe concentrations of chloral hydrate

are substantially greater than thosepresent in drinking water. Commentersalso questioned the need for an MCLGfor chloral hydrate because the MCLs forTHMs and HAAs and the treatmenttechnique of enhanced coagulation willadequately control for chloral hydrateand because there were no monitoringprovisions proposed. Other commentersargued that the use of a 10,000uncertainty factor and the selection ofthe Sanders et al. (1982) study as a basisfor setting the MCLG wereinappropriate.

In response, EPA agrees withcommenters that an MCLG for chloralhydrate is not needed. This is based onthe fact that the TTHM and HAA MCLsand the treatment technique (i.e.,enhanced coagulation/softening) willcontrol for chloral hydrate, as well asother chlorination byproducts. Inaddition, chloral hydrate does not serveas an important indicator for otherchlorination byproducts. The final rule,therefore, does not contain an MCLG forchloral hydrate. In light of this decision,EPA is not responding to comments onthe uncertainty factor used as the basisfor setting the MCLG.

10. MRDLG for Chlorinea. Today’s Rule. EPA is promulgating

an MRDLG of 4 mg/L for chlorine basedon a NOAEL from a chronic study inanimals.

b. Background and Analysis. EPAproposed an MRDLG of 4 mg/L forchlorine. The MRDLG was based on atwo-year rodent drinking water study inwhich chlorine was given to rats atdoses ranging from 4 to 14 mg/kg/dayand mice at doses ranging from 8 to 24mg/kg/day (NTP, 1990). Neithersystemic toxicity, nor effects on bodyweight and survival were found. Thus,the MRDLG was based on a NOAEL of14 mg/kg/day and application of a 100fold uncertainty factor to account forinter- and intra-species differences(EPA, 1994a). New information onchlorine has become available since the1994 proposal and was discussed in the1997 DBP NODA and is included in thepublic docket (EPA, 1997c). This newinformation did not contain data thatwould change the MRDLG. EPA hastherefore decided to finalize theproposed MRDLG of 4 mg/L forchlorine.

c. Summary of Comments. Severalcommenters agreed with EPA’sconclusion that there is no animalevidence of carcinogenicity for chlorine.Some commenters also agreed with EPAthat 4 mg/L was the appropriate MCLG.Several commenters agreed with theproposed relative source contribution of80 percent for chlorine. Some

commenters agreed with the uncertaintyfactor of 100 while others felt that it wastoo high. Some commenters encouragedEPA to consider children in estimatingrisk from chlorine.

In response, EPA believes that anuncertainty factor of 100 is appropriatewhen a NOAEL from a chronic animalstudy is the basis for the RfD. Becausecurrent methods for developing RfDs aredesigned to be protective for sensitivesubpopulations, the uncertainty factorof 100 is considered protective ofchildren. Furthermore, animal studiesindicate that chlorine is not adevelopmental toxicant.

11. MRDLG for Chloramine

a. Today’s Rule. EPA is promulgatingan MRDLG of 4 mg/L for chloraminesbased on a NOAEL from a chronicrodent study.

b. Background and Analysis. The1994 proposed Stage I DBPR includedan MRDLG for chloramines at 4 mg/Lbased on a NOAEL of 9.5 mg/kg/d forlack of toxicity in chronic rodentdrinking water study and on applicationof an uncertainty factor of 100 toaccount of inter- and intra-speciesdifferences (EPA, 1994h). Newinformation on chloramines has becomeavailable since the 1994 proposal andwas included in the 1997 DBP NODAand is included in the public docket(EPA, 1997c). This new information didnot contain data that would change theMRDLG. EPA has therefore decided tofinalized the proposed MRDLG of 4 mg/L for chloramines.

c. Summary of Comments. Severalcommenters agreed with the MRDLG of4 mg/L for chloramine (as chlorine).Some commenters felt that the MRDLGwas too low due to conservativeuncertainty factors. Many commentersagreed with EPA’s conclusion that thereis no animal evidence of carcinogenicityfor chloramines. Many commentersagreed with the RSC of 80% forchloramine while other believed thatthe RSC should be higher.

In response, EPA believes that theuncertainty factor of 100 in the MRDLGcalculation is appropriate to protectpublic health including that of childrenand sensitive subpopulations. EPAbelieves that the 80 percent is anappropriate ceiling for the RSC due tolack of exposure data on other sourcesof exposure.

B. Epidemiology

1. Cancer Epidemiology

a. Today’s Rule. EPA has evaluated allof the cancer epidemiology data and thecorresponding public commentsreceived on the 1994 proposal (EPA,


1994a), 1997 NODA (EPA, 1997b), and1998 NODA (EPA, 1998a). Based on thisevaluation, EPA believes that the cancerepidemiology data provides importantinformation that contributes to theweight-of-evidence evaluation on thepotential health risks from exposure tochlorinated drinking water. At this time,however, the cancer epidemiologystudies are insufficient to establish acausal relationship between exposure tochlorinated drinking water and cancer;and are thus considered limited for usein quantitative risk assessment. EPA’sweight-of-evidence evaluation of thepotential risk posed by chlorinateddrinking water is further discussed insection IV of this preamble.

b. Background and Analysis. Thepreamble to the 1994 proposed rulediscussed numerous cancerepidemiology studies that had beenconducted over the past 20 years toexamine the relationship betweenexposure to chlorinated water andcancer (EPA, 1994a). At the time of theregulatory negotiation, there wasdisagreement among the members of theReg. Neg. Committee on the conclusionsthat could be drawn from these studies.Some members of the Committee feltthat the cancer epidemiology data, takenin conjunction with the results fromtoxicological studies, provide ample andsufficient weight-of-evidence toconclude that exposure to DBPs indrinking water could result in increasedcancer risk at levels encountered insome public water supplies. Othermembers of the Committee concludedthat the cancer epidemiology studies onthe consumption of chlorinateddrinking water to date were insufficientto provide definitive information for theregulation.

In the 1998 DBP NODA (EPA, 1998a),EPA discussed several newepidemiology studies that had beenpublished since the 1994 proposal. EPAconcluded in the 1998 NODA, based ona review of all the cancer epidemiologystudies (including the more recentstudies), that a causal relationshipbetween exposure to chlorinated surfacewater and cancer has not yet beendemonstrated. However, several studieshave suggested a weak association invarious subgroups. Results from recentepidemiology studies continue tosupport the decision to pursueregulations to provide additional DBPcontrol measures as discussed in sectionIV.D of this preamble.

c. Summary of Comments. Severalcommenters agreed with EPA’scharacterization that there wasinsufficient evidence to conclude thatthere was a causal relationship betweenexposure to chlorinated surface water

and cancer. Other commentersdisagreed with this characterizationstating that they believed the evidencedid indicate there was a strongassociation between exposure tochlorinated water and cancer. Othercommenters stated that EPA had notclearly articulated the basis for itsconclusions on the issue of causality.

In response, EPA continues to believethat there is insufficient evidence, basedon the epidemiology data, to concludethere is a causal association betweenexposure to chlorinated waters andcancer. EPA agrees, however, that thebasis for its conclusion on causality wasnot clearly articulated. This judgementof causality was based on evaluating theexisting cancer epidemiologic databasefor the following criteria: strength ofassociation, consistency of the findings,specificity of the association, as well asother information concerning thetemporal sequence and presence of adose-response relationship, andbiological plausibility (Federal Focus,1996; EPA, 1986; EPA 1996b).

EPA applied the criteria stated aboveto assess the possible causality of cancerusing the best available cancerepidemiology studies (Cantor et al.,1985, McGeehin et al., 1993, King andMarrett, 1996, Cantor et al., 1998,Freedman et al., 1997, Hildesheim et al.,1998, Doyle et al., 1997). These studiesfound a weak association for bladdercancer, although the findings were notconsistent within and among thestudies. The specificity of theassociation, temporal association, anddose response relationship remainunknown. In addition, the biologicalmode of action has not beendetermined. Using the criteria forcausality, the present epidemiologicdata do not support a causalrelationship between exposure tochlorinated drinking water anddevelopment of cancer at this time. Thisconclusion does not preclude thepossibility that a causal link may beestablished at a later date by futureepidemiology and toxicology studies.

Some commenters argued that theepidemiological evidence indicated anincreased risk for cancer by exposure tochlorinated drinking water, while othersargued that the epidemiologicalevidence does not support a healtheffects concern. As stated above, EPAbelieves that, at this time, a causal linkbetween exposure to chlorinateddrinking water and development ofcancer cannot be determined. However,EPA believes that the epidemiologicalevidence suggests a potential increasedrisk for bladder cancer. It is thereforeprudent public health policy to protectagainst this potential public health

concern in light of the uncertainties andgiven the large population (over 200million people) potentially exposed.

2. Reproductive and DevelopmentalEpidemiology

a. Today’s Rule. EPA has evaluated allof the reproductive and developmentalepidemiology data and the publiccomments received on the 1994proposal, 1997 NODA, and the 1998NODA. Based on this evaluation, EPAbelieves that the reproductive anddevelopmental epidemiology dataprovides important information thatcontributes to the weight-of-evidenceevaluation on the potential risks fromexposure to chlorinated drinking water.However, the reproductiveepidemiology studies are insufficient toestablish a causal relationship betweenexposure to chlorinated drinking waterand reproductive and developmentaleffects and are limited for use in thequantification of risk.

b. Background and Analysis. In thepreamble to the 1994 proposed DBPR,EPA discussed several reproductiveepidemiology studies (EPA, 1994a). Atthe time of the proposal, EPA concludedthat there was no compelling evidenceto indicate a reproductive anddevelopmental hazard due to exposureto chlorinated water because theepidemiologic evidence was inadequateand the toxicological data were limited.In 1993, an expert panel of scientistswas convened by the International LifeSciences Institute to review theavailable human studies fordevelopmental and reproductiveoutcomes and to provide researchrecommendations (EPA/ILSI, 1993). Theexpert panel concluded that theepidemiologic results should beconsidered preliminary given that theresearch was at a very early stage (EPA/ILSI, 1993; Reif et al., 1996). The 1997NODA and the supporting documents(EPA, 1997c) presented several newstudies (Savitz et al., 1995; Kanitz et al.1996; and Bove et al., 1996) that hadbeen published since the 1994 proposedrule and the 1993 ILSI panel review.Based on the new studies presented inthe 1997 NODA, EPA stated that theresults were inconclusive with regard tothe association between exposure tochlorinated waters and adversereproductive and developmental effects(EPA, 1997b).

In the 1998 DBP NODA (EPA, 1998a),EPA included the recommendationsfrom an EPA convened expert panel inJuly 1997 to evaluate epidemiologicstudies of adverse reproductive ordevelopmental outcomes that may beassociated with the consumption ofdisinfected drinking water published


since the 1993 ILSI panel review. Areport was prepared entitled ‘‘EPAPanel Report and Recommendations forConducting Epidemiological Researchon Possible Reproductive andDevelopmental Effects of Exposure toDisinfected Drinking Water’’ (EPA,1998f). The 1997 expert panel was alsocharged to develop an agenda for furtherepidemiological research. The 1997panel concluded that the results ofseveral studies suggest that an increasedrelative risk of certain adverse outcomesmay be associated with the type of watersource, disinfection practice, or THMlevels. The panel emphasized, however,that most relative risks are moderate orsmall and were found in studies withlimitations in design or conduct. Thesmall magnitude of the relative riskfound may be due to one or moresources of bias, as well as to residualconfounding (factors not identified andcontrolled). Additional research isneeded to assess whether the observedassociations can be confirmed. Inaddition, the 1998 DBP NODA includeda summary of a study by Waller et al.(1998) conducted in California andanother study by Klotz and Pyrch (1998)conducted in New Jersey. EPAconcluded that while the Waller et al.(1998) study does not prove thatexposure to THMs in drinking watercauses early term miscarriages, it doesprovide important new information thatneeds to be explored and that the studyadds to the weight-of-evidence whichsuggests that exposure to DBPs mayhave an adverse health effect onhumans. EPA indicated that the reviewof the Klotz and Pyrch study (1998) hadnot been completed in time for the 1998NODA.

EPA has completed its review of theKlotz and Pyrch (1998) study andconcluded that the results in the reportprovide limited evidence to substantiatethe hypothesis that DBPs in drinkingwater cause adverse reproductive ordevelopmental effects since the bulk ofthe findings are inconclusive. There is,however, a suggestion in the study thattotal THMs or some other component ofsurface water is associated with a smallincreased risk of neural tube defects; nosignificant associations, however, wereobserved with individual THMs, HAAsor other composite measures ofexposure.

c. Summary of Comments. Severalcommenters agreed with EPA’sconclusions on the significance of thereproductive and developmental effectsfrom the various studies. Othersbelieved EPA had not accuratelycharacterized the potential adversereproductive and developmental effects

from exposure to DBPs in drinkingwater.

In response, EPA continues to believethat the available epidemiology dataalong with the toxicological findingssuggest that exposure to DBPs may haveadverse effects on humans. However,EPA believes the epidemiology evidenceis insufficient at this time to concludethat there is a causal associationbetween exposure to DBPs and adversereproductive and developmental effects.As noted in the 1998 NODA, EPA hasan epidemiology and toxicologyresearch program that is examining therelationship between exposure to DBPsand adverse reproductive anddevelopmental effects. In addition, EPAis pursuing appropriate follow-upstudies to see if the observed associationin the Waller et al. (1998) study can bereplicated elsewhere. EPA will also beworking with the California Departmentof Health Services to improve estimatesof exposure to DBPs in the existingWaller et al. study population. EPA willcollaborate with the Centers for DiseaseControl and Prevention (CDC) in a seriesof studies to evaluate if there is anassociation between exposure to DBPsin drinking water and birth defects. EPAis also involved in a collaborativetesting program with the NTP underwhich several individual DBPs havebeen selected for reproductive anddevelopmental laboratory animalstudies. This information will be usedin developing the Stage 2 DBPR.

C. MCLs and BAT for TTHM, HAA5,Chlorite, and Bromate; MRDLs and BATfor Chlorine, Chloramines, and ChlorineDioxide

MCLs are enforceable standardswhich are established as close to theMCLG as feasible. Feasible means withthe use of the best technology, treatmenttechniques, and other means which theAdministrator finds available (takingcosts into consideration) afterexamining for efficacy under fieldconditions and not solely underlaboratory conditions.

EPA is promulgating MCLs for twogroups of DBPs and two inorganicbyproducts. EPA is also promulgatingMRDLs for three disinfectants. EPA ispromulgating these MCLs and MRDLs atthe levels proposed in 1994. Systemswill determine compliance with theMCLs and MRDLs in the same manneras was proposed in 1994, except forchlorite. EPA determined thatadditional monitoring requirements forchlorite were necessary based on thefindings from the CMA two-generationreproductive and developmental study.

Along with introducing the concept ofthe MRDLG in the proposed rule, EPA

also introduced the MRDL for the threedisinfectants (chlorine, chloramines,and chlorine dioxide). The MRDLs areenforceable standards, analogous toMCLs, which recognize the benefits ofadding a disinfectant to water on acontinuous basis and to maintain aresidual to control for pathogens in thedistribution system. As with MCLs, EPAhas set the MRDLs as close to theMRDLGs as feasible. The Agency hasalso identified the BAT which isfeasible for meeting the MRDL for eachdisinfectant.

EPA received similar comments onthe use of the term MRDL as withMRDLG. The majority of commentersagreed with the use of the term MRDLfor the disinfectants and therefore EPAis using the term MRDL in the final rule.

1. MCLs for TTHMs and HAA5a. Today’s Rule. In today’s rule, EPA

is promulgating an MCL for TTHMs of0.080 mg/L. TTHM is the sum ofmeasured concentrations of chloroform,bromodichloromethane,dibromochloromethane, andbromoform. EPA is also promulgating anMCL for HAA5 of 0.060 mg/L. HAA5 isthe sum of measured concentrations ofmono-, di-, and trichloroacetic acids,and mono- and dibromoacetic acids. Asystem is in compliance with theseMCLs when the running annual averageof quarterly averages of all samplestaken in the distribution system,computed quarterly, is less than orequal to the MCL. If the running annualaverage computed for any quarterexceeds the MCL, the system is out ofcompliance. EPA believes that bymeeting MCLs for TTHMs and HAA5,water suppliers will also control theformation of other DBPs not currentlyregulated that may also adversely affecthuman health.

EPA has identified the best available(BAT) technology for achievingcompliance with the MCLs for bothTTHMs and HAA5 as enhancedcoagulation or treatment with granularactivated carbon with a ten minuteempty bed contact time and 180 dayreactivation frequency (GAC10), withchlorine as the primary and residualdisinfectant, as was proposed in 1994.

b. Background and Analysis. The1994 proposal for the Stage 1 DBPRincluded MCLs for TTHM and HAA5 at0.080 and 0.060 mg/L, respectively(EPA, 1994a). In addition to theproposed MCLs, subpart H systems—utilities treating either surface water orgroundwater under the direct influenceof surface water—that use conventionaltreatment (i.e., coagulation,sedimentation, and filtration) orprecipitative softening would be


required to remove DBP precursors byenhanced coagulation or enhancedsoftening. The removal of TOC would beused as a performance indicator for DBPprecursor control.

As part of the proposed rule, EPAestimated that 17% of PWSs wouldneed to change their treatment processto alternative disinfectants (ozone orchlorine dioxide) or advanced precursorremoval (GAC or membranes) in orderto comply with the Stage 1requirements. This evaluation wasimportant to assist in determiningwhether the proposed MCLs wereachievable and at what cost. Thisevaluation required an understanding ofthe baseline occurrence for the DBPsand TOC being considered in the Stage1 DBPR, an understanding of thebaseline treatment in-place, and anestimation of what treatmenttechnologies systems would use tocomply with the Stage 1 DBPRrequirements.

In 1997, at the direction of the M–DBPAdvisory Committee, the TWG reviewedMCL compliance predictions developedfor the 1994 proposal because ofconcern by several Committee membersthat modifications to the rule wouldresult in more PWSs not being able tomeet the new TTHM and HAA5 MCLswithout installation of higher costtechnologies such as ozone or GAC.Some members were concerned thatallowing disinfection inactivation creditprior to precursor removal (by enhancedcoagulation or enhanced softening) inorder to prevent significant reductionsin microbial protection would result inhigher DBP formation and force systemsto install alternative disinfectants oradvanced precursor removal to meet the1994 proposed TTHM and HAA5 MCLs.As discussed later in today’s documentin Section III.E (Preoxidation CT Credit),most PWSs can achieve significantreduction in DBP formation through thecombination of enhanced coagulation(or enhanced softening) whilemaintaining predisinfection. The TWG’sanalysis indicated that there would be adecrease in the percentage of PWSs thatwould need to install higher costtechnologies. This decrease wasattributed to changes in the proposedIESWTR which altered the constraintsby which systems could comply withthe MCLs. The requirements of theIESWTR would also prevent significantreduction in microbial protection asdescribed in the 1997 NODA (EPA,1997a) and elsewhere in today’s FederalRegister. EPA has included a discussionof the prediction of technology choicesin Section IV (Economic Analysis) oftoday’s rule and a more detaileddiscussion in the RIA for this rule (EPA,

1998g). EPA continues to believe theproposed MCLs are achievable withoutlarge-scale technology shifts.

c. Summary of Comments. Severalcommenters questioned whether theTTHM MCL of 0.080 mg/L and theHAA5 MCL of 0.060 mg/L were set at alevel that would preclude the use ofchlorine as an effective disinfectant.EPA does not believe the MCLs willpreclude the use of chlorine. Whilethere are currently systems that areexceeding these MCLs, the Agency hasconcluded that most systems will beable to achieve compliance by relativelylow cost alternatives such as: improvedDBP precursor removal throughenhanced coagulation or enhancedsoftening; moving the point ofdisinfection to reduce the reactionbetween chlorine and DBP precursors;the use of chloramines for residualdisinfection instead of chlorine; or acombination of these alternatives.

Many commenters also questioned theneed for a modified TTHM MCL and anew MCL for HAA5. As discussed insection I.B.2. of today’s rule, EPAbelieves the potential public health risksdo justify a reduction in exposure toDBPs and hence a modification in theMCL for TTHMs and a new MCL forHAA5. Also as discussed in section IVof this rule, EPA continues to believethat the potential risks associated withboth TTHM and HAA5 and unregulatedDBPs will be reduced by thecombination of these MCLs and DBPprecursor removal through enhancedcoagulation and enhanced softening.

While most commenters agreed withEPA’s definition of GAC10 and GAC20(GAC with a 10 and a 20 minute emptybed contact time, respectively), severalcommenters thought that designatingGAC as BAT meant that they wouldhave to install GAC at their treatmentplant. EPA is required to designate aBAT for any MCL that the Agencypromulgates; however, a system mayuse any technology it wants to complywith the MCL. However, a system mustinstall BAT prior to the State issuing avariance to one of these MCLs.

Commenters also questioned the useof group MCLs for TTHM and HAA5,instead of MCLs for the individualDBPs, since a group MCL does not takeinto account differing health effects andpotencies of individual DBPs. EPAcontinues to believe that regulatingTTHMs and HAAs as group MCLs isappropriate at this time for severalreasons. First, EPA does not haveadequate occurrence data for individualtrihalomethanes and haloacetic acids todevelop national occurrence estimateswhich are needed for estimating thepotential costs and benefits of the rule

(although the Agency has an adequatedatabase of group occurrence). Second,there is not an adequate understandingof how water quality parameters (suchas pH, temperature, bromide, andalkalinity) affect individual THM andHAA formation. Third, EPA does nothave an adequate understanding of howtreatment technologies control theformation of individual THMs andHAAs to enable specifying appropriateMCLs for individual TTHMs or HAAs atthis time. Finally, there are inadequatehealth data to characterize the potentialhealth risks for several of the HAAs andto then determine the potential benefitsfrom reduction in exposures. Inconclusion, EPA continues to believethe most appropriate approach forreducing the health risk from all DBPsis by the combination of TTHM andHAA5 MCLs and DBP precursorremoval.

Some commenters stated that EPAmay have underestimated HAAformation, especially in certain areas ofthe country. The Agency was aware thatwaters in particular regions of thecountry would be more difficult to treatin order to control for HAA5 than forTTHM. Based on additional datareceived since the proposal, EPAcontinues to believe that the HAA5 MCLcan be met by most systems through thesame general low-cost strategies as usedfor TTHM (e.g., improved DBPprecursor removal, moving the point ofdisinfection, use of chloramines forresidual disinfection) rather than highercost alternatives (see section IV.C forcost estimates of technology treatmentchoices).

Many commenters also requested thatStates be granted sufficient flexibility inimplementing this rule. While the Statemust adopt rules that are at least asstringent as those published in today’srule, EPA has given the States andsystems much latitude in monitoringplans (frequency and location),allowable disinfectants, and other ruleelements. Much of this flexibility carriesover from the 1979 TTHM Rule (EPA,1979).

Finally, some commenters stated thatrequirements in this rule arecomplicated. EPA acknowledges thatthis rule is complicated, but that thiscomplexity is necessary in order toadequately and economically addressthe potential DBP risks. EPA wasrequired to consider a host ofcomplicating factors in developingregulatory requirements: differentdisinfectants, different health effects(acute and chronic), different DBPformation kinetics, different sourcewater types and qualities, differenttreatment processes, and the need for


simultaneous compliance with otherrules such as the Total Coliform Rule,Lead and Copper Rule, and InterimEnhanced Surface Water TreatmentRule. The Agency chose to evaluate allthese factors by developingrequirements that minimized impactson various classes of systems whileenabling States to implement the rule.In addition to the further description ofthe requirements in today’s rule, EPAwill publish a State implementationmanual, a small system compliancemanual, and a series of guidancemanuals that will provide additionalinformation to systems and States inimplementing this rule.

EPA has reviewed all comments anddetermined that the requirementspromulgated today are necessary tocontrol the occurrence of TTHM andHAA5 and are feasible to achieve. Theserequirements take into account thedifficulties in simultaneouslycontrolling risks from DBPs andpathogens, while appropriatelyaddressing implementation andcompliance issues.

2. MCL for Bromatea. Today’s Rule. In today’s rule, EPA

is promulgating an MCL for bromate of0.010 mg/L. Bromate is one of theprincipal byproducts of ozonation inbromide-containing source waters. Theproposed MCL for bromate was 0.010mg/l. A system is in compliance withthe MCL when the running annualaverage of monthly samples, computedquarterly, is less than or equal to theMCL. If the running annual averagecomputed for any quarter exceeds theMCL, the system is out of compliance.EPA has identified the BAT forachieving compliance with the MCL forbromate as control of ozone treatmentprocess to reduce formation of bromate,as was proposed in 1994 (EPA, 1994a).

b. Background and Analysis. Forsystems using ozone, a separate MCLwas proposed for the primary inorganicDBP associated with ozone usage:bromate. Although the theoretical 10¥4

risk level for bromate is 0.005 mg/l, anMCL of 0.010 mg/L was proposedbecause available analytical detectionmethods for bromate were reliable onlyto the projected practical quantificationlimit (PQL) of 0.01 mg/L (EPA, 1994a).

In the preamble to the proposed rule,EPA requested comment on whetherthere were ways to set (or achieve) alower MCL (i.e., 0.005 mg/L [5 µg/L])and whether the PQL for bromate couldbe lowered to 5 µg/L in order to allowcompliance determinations for a lowerMCL in Stage 1 of the proposed rule.The proposed MCL of 0.010 mg/L forbromate was based on a projected PQL

that would be achieved by improvedmethods. The PQL of the revisedmethod is approximately 0.010 mg/L forbromate, as discussed in Section III.G(Analytical Methods). At the time of theNovember 1997 NODA, EPA was notaware of any new information thatwould lower the PQL for bromate andthus allow lowering the MCL. As aresult, EPA concluded that the proposedbromate MCL was appropriate.

c. Summary of Comments. Severalcommenters were concerned that thebromate MCL may have been set at alevel that would preclude the use ofozone. During the M–DBP AdvisoryCommittee discussions, the TWGevaluated the feasibility of ozone forcertain systems that were predicted tohave problems in complying with theTTHM and HAA5 MCLs. While ozonewas not feasible for all systems, it wasfeasible for many that did not haveelevated source water bromide levels toreact with ozone to form bromate. TheTWG predicted that most of the systemsnot able to use ozone would be able toswitch to chlorine dioxide for primarydisinfection.

EPA has reviewed all comments anddetermined that the requirementspromulgated today are necessary tocontrol the occurrence of bromate andare feasible to achieve. For additionaldiscussion on the treatmenttechnologies for controlling bromateformation and their costs see the Costand Technology Document forControlling Disinfectants andDisinfection Byproducts (EPA, 1998k).These requirements take into accountthe difficulties in simultaneouslycontrolling risks from DBPs andpathogens, while appropriatelyaddressing compliance andimplementation issues. In addition, theReg. Neg. Committee and the M–DBPAdvisory Committee supported theseconclusions.

3. MCL for Chloritea. Today’s Rule. In today’s rule, EPA

is promulgating an MCL for chlorite of1.0 mg/L. EPA has modified themonitoring requirements from theproposed rule for the reasons discussedin section III.A.7. The issue ofmonitoring and MCL compliancedeterminations as they relate to thehealth effect of concern for chlorite werediscussed in the proposed rule (EPA,1994a). CWSs and NTNCWSs usingchlorine dioxide for disinfection oroxidation are required to conductsampling for chlorite both daily at theentrance to the distribution system andmonthly (3 samples on the same day)within the distribution system.Additional distribution system

monitoring is required when thechlorite concentration measured at theentrance to the distribution systemexceeds a chlorite concentration of 1.0mg/L. Distribution system monitoringmay be reduced if certain conditions aremet (described in section III.H of thisrule).

b. Background and Analysis. Forsystems using chlorine dioxide, EPAproposed a separate MCL for chloriteassociated with its usage in 1994. Theproposed chlorite MCL of 1.0 mg/L wassupported by the Reg. Neg. Committeebecause 1.0 mg/L was the lowest levelconsidered practicably achievable bytypical systems using chlorine dioxide,from both treatment and monitoringperspectives. The MCLG was 0.08 mg/L, due (in part) to data gaps thatrequired higher uncertainty factors inthe MCLG determination. The CMAagreed to fund new health effectsresearch on chlorine dioxide andchlorite—with EPA approval of theexperimental design—to resolve thesedata gaps. EPA completed its review ofthe study and published its findings ina NODA in March 1998. Those findingsled to a chlorite MCLG of 0.8 mg/L andsupport for an MCL of 1.0 mg/L.

c. Summary of Comments. Manycommenters requested that EPA notmodify the MCL for chlorite prior toreceipt and evaluation of the CMAstudy, since lowering the MCL couldpreclude the use of chlorine dioxide fordrinking water disinfection. EPA hasevaluated the CMA study andconcluded that the MCLG for chloriteshould be 0.8 mg/L. EPA believes theproposed MCL of 1.0 mg/L, based on athree sample average to determinecompliance, is appropriate because thisis the lowest level achievable by typicalsystems using chlorine dioxide. Inaddition, considering the margin ofsafety that is factored into the estimateof the MCLG, EPA believes the MCLwill be protective of public health. Oncethe final MCLG was established, EPAdecided that the chlorite MCL should befinalized at the level proposed whichwas as close as economically andtechnically feasible to the MCLG, andmodified the proposed requirements formonitoirng and compliance in responseto the health concerns associated withchlorite.

EPA has reviewed all comments anddetermined that the requirementspromulgated today are necessary tocontrol the occurrence of chlorite andare feasible to achieve. Theserequirements take into account thedifficulties in simultaneouslycontrolling risks from DBPs andpathogens, while appropriatelyaddressing compliance and


implementation issues. In addition, theReg. Neg. Committee and the M–DBPAdvisory Committee supported theseconclusions.

4. MRDL for Chlorinea. Today’s Rule. Chlorine is a widely

used and highly effective waterdisinfectant. In today’s rule, EPA ispromulgating an MRDL for chlorine of4.0 mg/L. As a minimum, CWSs andNTNCWSs must measure the residualdisinfectant level at the same points inthe distribution system and at the sametime as total coliforms, as specified in§ 141.21. Subpart H systems may use theresults of residual disinfectantconcentration sampling done under theSWTR (§ 141.74(b)(6) for unfilteredsystems, § 141.74(c)(3) for systems thatfilter) in lieu of taking separate samples.Monitoring for chlorine may not bereduced.

A system is in compliance with theMRDL when the running annual averageof monthly averages of all samples,computed quarterly, is less than orequal to the MRDL. Notwithstanding theMRDL, operators may increase residualchlorine levels in the distributionsystem to a level and for a timenecessary to protect public health toaddress specific microbiologicalcontamination problems (e.g., includingdistribution line breaks, storm runoffevents, source water contamination, orcross-connections).

EPA has identified the best meansavailable for achieving compliance withthe MRDL for chlorine as control oftreatment processes to reducedisinfectant demand, and control ofdisinfection treatment processes toreduce disinfectant levels.

b. Background and Analysis. The1994 proposed Stage I DBPR includedan MRDL for chlorine at 4.0 mg/L (EPA,1994a). The MRDL for chlorine is equalto the MRDLG for chlorine. EPArequested comment on a number ofissues relating to the calculation of theMRDLG for chlorine. New informationon chlorine has become available sincethe 1994 proposal and was discussed inthe 1997 NODA (EPA, 1997b). EPAbelieves that no new information hasbecome available to warrant changingthe proposed MRDL. EPA has thereforedecided to promulgate the MRDL of 4.0mg/L for chlorine.

c. Summary of Comments. Somecommenters expressed concern that theMRDL for chlorine is too high. Thesecommenters were concerned that 4 mg/L levels of chlorine would have adetrimental effect on piping materialsand would cause taste and odorproblems. One commenter supportedthe chlorine MRDL and the methods of

calculating compliance with the MRDL.This commenter felt that 4.0 mg/Lappropriately allows for disinfectionunder varying circumstances. Onecommenter requested that EPA increasethe flexibility of utilities to meet theMRDL for chlorine during periods whenchlorine levels in the distributionsystems may need to be raised to protectpublic health.

EPA believes that the MRDL of 4.0mg/L for chlorine is appropriate tocontrol for potential health effects(MRDLG is 4.0 mg/L) from chlorinewhile high enough to allow for controlof pathogens under a variety ofconditions. EPA also believes thatcompliance based on a running annualaverage of monthly averages of allsamples, computed quarterly issufficient to allow systems to increaseresidual chlorine levels in thedistribution system to a level and for atime necessary to protect public healthto address specific microbiologicalcontamination problems and stillmaintain compliance. If a system hastaste and odor problems associated withexcess chlorine levels it can lower itslevel of chlorine. Since there may not beany health effects associated with tasteand odor problems, EPA does not havea statutory requirement to address thisconcern.

5. MRDL for Chloramines

a. Today’s Rule. Chloramines areformed when ammonia is added duringchlorination. In today’s rule, EPA ispromulgating an MRDL for chloraminesof 4.0 mg/L (measured as combined totalchlorine). As a minimum, CWSs andNTNCWSs must measure the residualdisinfectant level at the same points inthe distribution system and at the sametime as total coliforms, as specified in§ 141.21. Subpart H systems may use theresults of residual disinfectantconcentration sampling done under theSWTR (§ 141.74(b)(6) for unfilteredsystems, § 141.74(c)(3) for systems thatfilter) in lieu of taking separate samples.Monitoring for chloramines may not bereduced.

A PWS is in compliance with theMRDL when the running annual averageof monthly averages of all samples,computed quarterly, is less than orequal to the MRDL. Notwithstanding theMRDL, operators may increase residualchloramine levels in the distributionsystem to a level and for a timenecessary to protect public health toaddress specific microbiologicalcontamination problems (e.g., includingdistribution line breaks, storm runoffevents, source water contamination, orcross-connections).

EPA has identified the best meansavailable for achieving compliance withthe MRDL for chloramines as control oftreatment processes to reducedisinfectant demand, and control ofdisinfection treatment processes toreduce disinfectant levels.

b. Background and Analysis. The1994 proposed Stage 1 DBPR includedan MRDL for chloramines at 4.0 mg/L(EPA, 1994a). The MRDL forchloramines is equal to the MRDLG forchloramines. EPA requested commenton a number of issues relating to thecalculation of the MRDLG forchloramines. New information onchloramines has become available sincethe 1994 proposal and was cited in the1997 NODA and is included in thepublic docket for this rule (EPA, 1997b).This new information did not containdata that would warrant changing theMRDL. EPA has therefore decided topromulgate the proposed MRDL of 4.0mg/L for chloramines.

c. Summary of Comments. Somecommenters remarked that systems withhigh concentrations of ammonia wouldhave difficulty meeting the MRDL forchloramine of 4.0 mg/L and stillmaintain adequate microbial protection.One commenter felt that there shouldnot be a limit for chloramine residualdue to variations in parameters such asdistribution system configurations andtemperature. One commenter felt thatthe MRDL for chloramines was too lowand should not be set at the same levelas the chlorine MRDL since chlorine isa stronger disinfectant thanchloramines. This commenter felt thatlimiting the chloramine residual wouldreduce the capability to sustain highwater quality in the distribution system.One commenter supported thechloramine MRDL and the methods ofcalculating compliance with the MRDL.This commenter felt that 4.0 mg/Ladequately allows for disinfection undervarying circumstances.

EPA believes that compliance basedon a running annual average of monthlyaverages of all samples, computedquarterly, is sufficient to allow systemsto increase residual chloramine levels inthe distribution system to a level and fora time necessary to protect public healthto address specific microbiologicalcontamination problems and stillmaintain compliance. The MRDL forchloramine does not limit disinfectantdosage but rather disinfectant residualin the distribution system. EPAtherefore, believes that systems withhigh levels of ammonia should be ableto comply with the MRDL. Systems thathave difficulty sustaining high waterquality in the distribution systemshould consider modifying their


treatment or maintenance procedures toreduce demand. Although chlorine is astronger disinfectant than chloramine,EPA believes that an MRDL of 4.0 mg/L is sufficient to provide adequatemicrobial protection.

6. MRDL for Chlorine Dioxidea. Today’s Rule. Chlorine dioxide is

used primarily for the oxidation of tasteand odor-causing organic compounds inwater. It can also be used for theoxidation of reduced iron andmanganese and color, and as adisinfectant and algicide. Chlorinedioxide reacts with impurities in watervery rapidly, and is dissipated quickly.In today’s rule, EPA is promulgating anMRDL of 0.8 mg/L for chlorine dioxide.Unlike chlorine and chloramines, theMRDL for chlorine dioxide may not beexceeded for short periods of time toaddress specific microbiologicalcontamination problems because ofpotential health concerns with short-term exposure to chlorine dioxide abovethe MCL.

CWSs and noncommunity systemsmust monitor for chlorine dioxide onlyif chlorine dioxide is used by the systemfor disinfection or oxidation. Monitoringfor chlorine dioxide may not bereduced. If monitoring is required,systems must take daily samples at theentrance to the distribution system. Ifany daily sample taken at the entranceto the distribution system exceeds theMRDL, the system is required to takethree additional samples in thedistribution system on the next day.Systems using chlorine as a residualdisinfectant and operating boosterchlorination stations after the firstcustomer must take three samples in thedistribution system: one as close aspossible to the first customer, one in alocation representative of averageresidence time, and one as close aspossible to the end of the distributionsystem (reflecting maximum residencetime in the distribution system).Systems using chlorine dioxide orchloramines as a residual disinfectant orchlorine as a residual disinfectant andnot operating booster chlorinationstations after the first customer musttake three samples in the distributionsystem as close as possible to the firstcustomer at intervals of not less than sixhours.

If any daily sample taken at theentrance to the distribution systemexceeds the MRDL and if, on thefollowing day, any sample taken in thedistribution system also exceeds theMRDL, the system will be in acuteviolation of the MRDL and must takeimmediate corrective action to lower theoccurrence of chlorine dioxide belowthe MRDL and issue the required acutepublic notification. Failure to monitorin the distribution system on the dayfollowing an exceedance of the chlorinedioxide MRDL shall also be consideredan acute MRDL violation.

If any two consecutive daily samplestaken at the entrance to the distributionsystem exceed the MRDL, but none ofthe samples taken in the distributionsystem exceed the MRDL, the systemwill be in nonacute violation of theMRDL and must take immediatecorrective action to lower theoccurrence of chlorine dioxide belowthe MRDL. Failure to monitor at theentrance to the distribution system onthe day following an exceedance of thechlorine dioxide MRDL shall also beconsidered a nonacute MRDL violation.

EPA has identified the best meansavailable for achieving compliance withthe MRDL for chlorine dioxide ascontrol of treatment processes to reducedisinfectant demand, and control ofdisinfection treatment processes toreduce disinfectant levels.

b. Background and Analysis. EPAproposed an MRDL for chlorine dioxideof 0.8 mg/L in 1994. The MRDL wasdetermined considering the tradeoffsbetween chemical toxicity and thebeneficial use of chlorine dioxide as adisinfectant. The Reg. Neg. Committeeagreed to this MRDL with thereservation that it would be revisited, ifnecessary, after completion of a two-generation reproductive study by CMA.

As discussed above for chlorite, atwo-generation reproductive study onchlorite, which is relevant to healtheffects of chlorine dioxide, wascompleted by the CMA. EPA completedits review of this study and publishedits findings in a NODA in March 1998(EPA, 1998a). Based on its assessment ofthe CMA study and a reassessment ofthe noncancer health risk for chloriteand chlorine dioxide, EPA concludedthat the MRDLG for chlorine dioxide bechanged from 0.3 mg/L to 0.8 mg/L.

Since this new MRDLG was equal to theproposed MRDL for chlorine dioxide,the MRDL will remain 0.8 mg/L.

c. Summary of Comments. A numberof commenters were concerned that theMRDL for chlorine dioxide not belowered below the proposed level of 0.8mg/L because this would preclude theuse of chlorine dioxide as a waterdisinfectant. One commenter supportedthe MRDL for chlorine dioxide based onpublic health protection, adequatemicrobial protection, and technicalfeasibility. One commenter agreed that arunning annual average of samples forcompliance determination should not beallowed for chlorine dioxide. Onecommenter was concerned that thechlorine dioxide MRDL was too highand that EPA should consider childrenand vulnerable populations inestablishing drinking water standards.

EPA has reassessed the health effectsdata on chlorine dioxide, including thenew CMA two-generation study anddetermined that the MRDL shouldremain at 0.8 mg/L as proposed. EPAbelieves that this MRDL is set at atechnically feasible level for themajority of chlorine dioxide plants. Thisis the case because EPA consideredchildren and susceptible populations inits MRDLG determination (EPA, 1998h).The MRDL is set as close to this MRDLGas is technically and economicallyfeasible.

D. Treatment Technique Requirement

1. Today’s Rule

Today’s rule establishes treatmenttechnique requirements for removal ofTOC to reduce the formation of DBPs bymeans of enhanced coagulation orenhanced softening. The treatmenttechnique applies to Subpart H systemsusing conventional filtration treatmentregardless of size. Subpart H systems aresystems with conventional treatmenttrains that use surface water or groundwater under the influence of surfacewater as their source. The treatmenttechnique requirement has two steps ofapplication. Step 1 specifies thepercentage of influent TOC a plant mustremove based on the raw water TOC andalkalinity levels. The matrix in TableIII–1 specifies the removal percentages.

TABLE III–1.—REQUIRED REMOVAL OF TOTAL ORGANIC CARBON BY ENHANCED COAGULATION AND ENHANCEDSOFTENING FOR SUBPART H SYSTEMS USING CONVENTIONAL TREATMENT a,b

Source water TOC (mg/L)

Source water alkalinity (mg/L as CaCO3)

0–60 (percent) >60–120 (per-cent)

>120 c (per-cent)

>2.0–4.0 ....................................................................................................................................... 35.0 25.0 15.0


TABLE III–1.—REQUIRED REMOVAL OF TOTAL ORGANIC CARBON BY ENHANCED COAGULATION AND ENHANCEDSOFTENING FOR SUBPART H SYSTEMS USING CONVENTIONAL TREATMENT a,b—Continued

Source water TOC (mg/L)

Source water alkalinity (mg/L as CaCO3)

0–60 (percent) >60–120 (per-cent)

>120 c (per-cent)

>4.0–8.0 ....................................................................................................................................... 45.0 35.0 25.0>8.0 .............................................................................................................................................. 50.0 40.0 30.0

a Systems meeting at least one of the conditions in Section 141.135(a)(2) (i)–(vi) of the rule are not required to meet the removals in this table.b Softening systems meeting one of the two alternative compliance criteria in Section 141.135(a)(3) of the rule are not required to meet the re-

movals in this table.c Systems practicing softening must meet the TOC removal requirements in the last column to the right.

Step 2 provides alternate performancecriteria when it is technically infeasiblefor systems to meet the Step 1 TOCremoval requirements. For systemspracticing enhanced coagulation, Step 2of the treatment technique requirementis used to set an alternative TOCremoval requirement (i.e. alternativepercent removal of raw water TOC) forthose systems unable to meet the TOCremoval percentages specified in thematrix. The alternative TOC removalpercentage is determined by performingjar tests on at least a quarterly basis forone year. During the jar tests, alum oran equivalent dose of ferric coagulant isadded in 10 mg/L increments until thepH is lowered to the target pH value.The target pH is the value the samplemust be at or below before theincremental addition of coagulant canbe discontinued. For the alkalinityranges 0–60, >60–120, >120–240, and>240 mg/L (as CaCO3), the target pHvalues are 5.5, 6.3, 7.0, and 7.5,respectively. Once the Step 2 jar test iscomplete, the TOC removal (mg/L) isthen plotted versus coagulant dose (mg/L). The alternative TOC removalpercentage is set at the point ofdiminishing returns (PODR) identifiedon the plot.

Today’s rule defines the PODR as thepoint on the TOC versus coagulant doseplot where the slope changes fromgreater than 0.3/10 to less than 0.3/10and remains less than 0.3/10. Afteridentifying the PODR, the alternativeTOC removal percentage can be set. Ifthe TOC removal versus coagulant doseplot does not meet the PODR definition,the water is considered not amenable toenhanced coagulation and TOC removalis not required if the PWS requests, andis granted, a waiver from the enhancedcoagulation requirements by the State.Systems are required to meet thealternative TOC removal requirementsduring full-scale operation to maintaincompliance with the treatmenttechnique. For the technical reasonsoutlined in the 1997 DBP NODA (EPA1997b), EPA has concluded that thisdefinition of the PODR is a reliable

indicator of the amount of TOC that isfeasible to remove.

Systems practicing enhancedsoftening are not required to perform jartesting under today’s treatmenttechnique as part of a Step 2 procedure.Rather, they are required to meet one ofthree alternative performance criteria ifthey cannot meet the Step 1 TOCremoval requirements. These criteriaare: (1) Produce a finished water with aSUVA of less than or equal to 2.0 L/mg-m; (2) remove a minimum of 10 mg/Lmagnesium hardness (as CaCO3); or (3)lower alkalinity to less then 60 mg/L (asCaCO3). All three of these alternativeperformance criteria are measuredmonthly and can be calculated quarterlyas a running annual average todemonstrate compliance. As discussedin the 1997 DBP NODA (EPA 1997b)EPA has not been able, from a technicaland engineering standpoint, to identifya Step 2 testing procedure at this timethat allows softening systems to set analternative TOC removal amount.Enhanced softening systems unable tomeet the Step 1 TOC removalrequirements or any of the threealternative performance criteria mayapply to the State for a waiver from thetreatment technique requirements. EPAbelieves the three alternativeperformance criteria listed aboveprovide assurance that softeningsystems have maximized TOC removalto the extent feasible.

Today’s rule also provides alternativecompliance criteria—which are separateand independent of the Step 2 enhancedcoagulation procedure and theenhanced softening alternativeperformance criteria—from thetreatment technique requirementsprovided certain conditions are met.These criteria are:

(1) the system’s source water TOC is<2.0 mg/L;

(2) the system’s treated water TOC is<2.0 mg/L;

(3) the system’s source water TOC<4.0 mg/L, its source water alkalinity is>60 mg/L (as CaCO3), and the system isachieving TTHM <40µg/L and HAA5

<30µg/L (or the system has made a clearand irrevocable financial commitmentto technologies that will meet the TTHMand HAA level);

(4) the system’s TTHM is <40µg/L,HAA5 is <30µg/L, and only chlorine isused for primary disinfection andmaintenance of a distribution systemresidual;

(5) the system’s source water SUVAprior to any treatment is ≤ 2.0 L/mg–m;and

(6) the system’s treated water SUVA is≤ 2.0 L/mg–m.

Alternative compliance criteria 1, 2, 5,and 6 are determined based on monthlymonitoring calculated quarterly as arunning annual average of allmeasurements. Alternative compliancecriteria 3 is based on monthlymonitoring for TOC and alkalinity orquarterly monitoring for TTHMs andHAA5, calculated quarterly as a runningannual average of all measurements.Alternative criteria 4 is determinedbased on monitoring for TTHMs andHAA5, calculated quarterly as a runningannual average of all measurements.SUVA, an indicator of DBP precursorremoval treatability, is defined as theUV–254 (measured in m¥1) divided bythe DOC concentration (measured asmg/L).

2. Background and AnalysisThe general structure of the 1994

proposed rule and today’s final rule aresimilar. The 1994 proposal included anenhanced coagulation and enhancedsoftening treatment techniquerequirement for Subpart H systems. The1994 proposed rule included a TOCremoval matrix for Step 1 TOC removalrequirements and it also provided for aStep 2 jar test procedure for systemspracticing enhanced coagulation. ThePODR for the Step 2 procedure wasdefined as a slope of .3/10 on the TOCremoval versus coagulant dose plot. TheStep 2 procedure included a maximumpH value, now referred to as the ‘‘targetpH’’ for conducting the jar tests and italso allowed systems to request a waiverfrom the State if the PODR was never


attained. The target pH values in the1994 proposal were the same as those intoday’s final rule. A Step 2 procedurefor enhanced softening systems was notspecified in the proposal.

The proposed rule also provided for anumber of exceptions to the enhancedcoagulation and enhanced softeningrequirements, but it did not include useof SUVA as an alternative compliancecriteria.

A major goal of the TOC removaltreatment technique requirements wasto minimize transactional costs to theStates both in terms of limiting thenumber of systems seeking alternativeperformance criteria and in providingrelatively simple methodologies fordetermining alternative performancecriteria. In the 1997 DBP NODA (EPA1997b), EPA presented new data andanalysis and the basis for modifying theproposed criteria to those described intoday’s final rule. The 1997 NODA alsosolicited public comment on EPA’sintended changes to the proposal andthe recommendations of the M–DBPAdvisory Committee to EPA. Anoverview of the key points in the 1997NODA most pertinent to modifying thetreatment technique requirements arepresented below.

Data Supporting Changes in the TOCRemoval Requirements. The proposedTOC removal percentages, which wereset with the intent that 90% of affectedsystems would be able to achieve them,were developed with limited data. Sincethe proposal, several jar studies andanalyses of full-scale plant TOC removalperformance have been performed. Theywere analyzed by EPA as part of the M–DBP Advisory Committee process. Thisdata will not be thoroughly reviewedhere; instead, the major points salient todevelopment of the final regulation willbe summarized. See the 1997 DBPNODA (EPA 1997b) to review EPA’sdetailed analysis of the new data.

As discussed in greater detail in the1997 DBP NODA, research by Singer etal. (1995) indicated that a significantnumber of waters, especially low-TOC,high-alkalinity waters in the first row ofthe proposed TOC removal matrix,would probably not be able to meet theTOC removal percentages and wouldtherefore need to use the Step 2 protocolto establish alternative performancecriteria. The Singer et al. (1995) studyraised concern regarding the number ofsystems that might need to use the Step2 procedure to set alternativeperformance criteria. A study byMalcolm Pirnie, Inc. and ColoradoUniversity addressed this issue bydeveloping a nationally representativedatabase of 127 source waters and usedthis data to develop a model to predict

enhanced coagulation’s ability toremove TOC from different sourcewaters (Edwards, 1997; Tseng &Edwards, 1997; Chowdhury, 1997). Themodel was subsequently used to analyzethe level or percentage of TOC removalthat is operationally feasible to achievefor the boxes in the proposed TOCremoval matrix. Nine predictiveequations for TOC removal weredeveloped, one for each box of the TOCremoval matrix, to select TOC removalpercentages that could be ‘‘reasonably’’met by 90 percent of the systemsimplementing enhanced coagulation.The equations indicated that manysystems having source waters within thelow TOC boxes of the matrix (i.e. 2.0–4.0 mg/L, the first row of the matrix)would meet the Step 2 slope criterionbefore meeting the required TOCremoval percentages. In other words,less than 90 percent of the systems inthis row could achieve the proposedTOC removal with reasonable coagulantdoses. The equations indicated that theTOC removal percentages in themedium and high TOC boxes (thebottom two rows of the matrix) could bemet by approximately 90 percent of thesystems in these boxes. The researchteam also examined 90th-percentileSUVA curves, in conjunction with thenine TOC removal curves, to predictwhat TOC removal percentage isappropriate for each of the nine boxesof the matrix.

An analysis of full-scale TOC removalhas also been performed since 1994.Data was obtained from 76 treatmentplants of the American Water WorksService Company (AWWSCo) system,plants studied by Randtke et al. (1994),and plants studied by Singer et al.(1995). These data represent a one-timesampling at each plant under currentoperating conditions when enhancedcoagulation was not being practiced.This sampling is different from theproposed compliance requirementswhich would be based on an annualaverage of monthly samples. Based oncurrent treatment at the plants in thestudy, 83 percent of the systems treatingmoderate-TOC, low-alkalinity waterremoved an amount of TOC greater thanthat required by the TOC removalmatrix, whereas only 14 percent of thesystems treating water with low TOCand high alkalinity met the proposedTOC removal requirements. The resultsof the survey, coupled with theinformation discussed in the precedingparagraph, indicate that the proposedTOC removal percentages in the top rowof the matrix might be too high for 90percent of plants to avoid the Step 2procedure, while the removal

percentages in the bottom two rows maybe reasonable and allow 90 percent ofplants to avoid the Step 2 procedure.Therefore, the TOC removal percentagesin the first row have been lowered 5.0percentage points to enable 90 percentof plants to comply withoutunreasonable coagulant dosage orresorting to the Step 2 procedure.

Data Supporting the Use of SUVA asan Exemption from TreatmentTechnique Requirements. At the time ofthe proposal, insufficient data on SUVAwas available to define precise criteriafor when enhanced coagulation wouldnot be effective for removing DBPprecursors. The M–DBP AdvisoryCommittee examined the role of SUVAas an indicator of the amount of DBPprecursor material enhancedcoagulation is capable of removing. Ithas been well established thatcoagulation primarily removes thehumic fraction of the natural organicmatter (NOM) in water (Owen et al.,1993). Furthermore, Edzwald and VanBenschoten (1990) have found SUVA tobe a good indicator of a water’s humiccontent. The humic fraction of a water’sorganic content significantly affects DBPformation upon chlorination.

A study by White et al. (1997) showedthat waters with high initial SUVAvalues exhibited significant reductionsin SUVA as a result of coagulation,demonstrating a substantial removal ofthe humic (and other UV-absorbing)components of the organic matter,whereas waters with low initial SUVAvalues exhibited relatively lowreductions in SUVA. For all of thewaters examined, the SUVA tended toplateau at high alum doses, reflectingthat the residual organic matter wasprimarily non-humic and thereforeunamenable to removal by enhancedcoagulation. SUVA’s ability to indicatethe amount of humic matter present,and enhanced coagulation’s ability topreferentially remove humic matter,logically establishes SUVA as anindicator of enhanced coagulation’sability to remove humic substances froma given water. The M–DBP AdvisoryCommittee therefore recommended thata SUVA value ≤ 2.0 L/mg–m be anexemption from the treatment techniquerequirement and that this SUVA valuealso be added as a Step 2 procedure.

Effect of Coagulant Dose on TOCRemoval for Enhanced Softening. At thetime of proposal, limited data wasavailable on the effectiveness of TOCremoval by enhanced coagulation andenhanced softening and on conditionsthat define feasibility. Several studiesexamined the relationship betweenincreased coagulant dose and TOCremoval (Shorney et al., 1996; Clark et


al. 1994). These studies indicate someimprovement in TOC removal withsmall doses of iron salts (5 mg/L ferricsulfate), but no additional TOC removalduring softening occurred withincreased coagulant addition (up to 25mg/L dose). Pilot testing by the City ofAustin’s softening plant confirmed thestudy’s jar test results by showing thatincreasing ferric sulfate doses beyondthe level required for turbidity removalprovided no additional TOC removal.

Multiple jar tests on various watersperformed by Singer et al. (1996)examined the relationship between useof lime and soda ash and TOC removal.Only lime and soda ash (no coagulants)were used in the tests. The studyshowed the removal of 10 mg/L ofmagnesium hardness would probablyhave less of an impact on plant residualgeneration than using a lime soda-ashprocess. However, the amount ofresidual material generated under bothscenarios could be substantial.

Step 2 Requirements for SofteningSystems. As stated above, the proposedrule did not include a Step 2 procedurefor softening plants because of a lack ofdata. The M-DBP Advisory Committeeexamined new data that had beencollected since the proposal todetermine if a Step 2 procedure forsoftening plants could be identified.Data included the current TOC removalsbeing achieved by softening plantscovered by the ICR (49 plants). The datawere analyzed to find the appropriateTOC removal levels for softening plants.The results of plotting the average TOCpercent removals on a percentile basisindicated that the relative impact ofmeeting the TOC removal requirementin the proposed rule would be greatestin the low TOC group (>2–4 mg/L).However, forcing a plant to increase pHmay require it to add soda ash (due tothe decrease in alkalinity caused byhigh lime dose necessary to raise thepH). This would be a significanttreatment change due to the additionalsolids generation and becausesignificant amounts of magnesiumhydroxide may precipitate at the higherpH. Most softening plants are normallyoperated without soda ash additionbecause of the high cost of soda ash, theadditional sludge production, theincreased chemical addition to stabilizethe water, and the increased sodiumlevels in the finished water (Randtke etal., 1994 and Shorney et al., 1996). Dueto these difficulties, EPA does notcurrently believe that a lime and soda-ash softening process would be a viableStep 2 procedure for softening systems.The final rule instead specifies twoalternative compliance criteria,

mentioned earlier in this section, as aStep 2 procedure for softening systems.

3. Summary of CommentsA large number of comments on the

1994 proposal questioned whether therequired TOC removal percentagescould be obtained by 90 percent ofaffected systems. In response, since thetime of proposal, a large body ofadditional data and analysis has beendeveloped to help address this question.The analyses discussed above showedthat the top row of the TOC removalmatrix needed to be lowered by 5.0percentage points to enable 90 percentof systems within the row to achieve therequired TOC removal withoutunreasonable coagulant doses. Analysisalso showed the TOC removalpercentages contained in the two lowerrows of the TOC removal matrixaccurately reflected the TOC removal 90percent of these systems could remove.EPA believes the final TOC removalmatrix, which includes the adjustmentsto the top row mentioned above,accurately reflects the TOC removal that90 percent of the systems affected by therule could practically achieve.

Commenters questioned why systemsthat meet the DBP Stage 1 MCLs forTTHM and HAA5 must still practiceenhanced coagulation. The enhancedcoagulation treatment technique isdesigned to remove DBP precursormaterial to help reduce the risks posedby DBPs. Also, EPA believes thatenhanced coagulation would reduce thenumber of systems switching toalternative disinfectants, which was agoal of the Reg. Neg. Committee. EPAbelieves that even if systems are meetingthe MCLs, an additional risk reductionbenefit can be achieved through removalof DBP precursor material at a relativelylow cost to the system. Therefore,systems that meet the MCLs must stillpractice enhanced coagulation todecrease the risks posed by DBPs ingeneral.

The Agency received numerouscomments on the 1994 proposal thatexpressed doubt regarding the definitionof the PODR. Specifically, thecommenters stated that the accuracy ofthe slope criterion (0.3 mg/L TOCremoved per 10 mg/L coagulant added)for determining the PODR was notsupported with adequate data. The datadeveloped since the proposal and thecorresponding analysis demonstrate thatthe slope criterion accurately predictsthe PODR. The analyses discussedabove showed that there is a particularrelationship between SUVA and theslope criterion, namely, that they bothpredict the PODR at the same point ofthe TOC removal versus coagulant dose

curve. Since SUVA is a very goodpredictor of the humic fraction of TOC,which is the fraction preferentiallyremoved by enhanced coagulation, andthe PODR predicted by SUVA and theslope criterion agree, EPA believes theslope criterion of 0.3 mg/L TOC removalper 10 mg/L of coagulant additionaccurately predicts the PODR.

The majority of commenters did notsupport requiring the use of bench-scalefiltration as part of the Step 2 enhancedcoagulation procedure. The commentersgenerally believed that using filtration atbench scale is of limited value becausethe great majority of TOC is removed viasedimentation, not through filtration.Additionally, some commentors felt thatattempting to replicate full-scalefiltration at bench scale can containinherent inaccuracy. EPA generallyagrees that a Step 2 filtration procedureshould not be required. The Agencybelieves that most of the TOC removedby conventional treatment plants isremoved in the sedimentation basinrather than in the filters. Therefore,requiring a bench-scale filtrationprocedure as part of Step 2 testing willnot increase the accuracy of theprocedure or its value to the treatmenttechnique implementation. Accordingly,today’s final rule does not require theuse of a bench scale filtration procedureduring Step 2 enhanced coagulationtesting. Detailed guidance onconducting the Step 2 testing will beprovided in the Guidance Manual forEnhanced Coagulation and EnhancedPrecipatative Softening.

Commenters expressed variedopinions regarding the frequency ofStep 2 testing. Several commentersstated that the rule should not set aminimum testing frequency, but that itshould be left to State discretion basedon source water characteristics. Othercommenters believed a minimum ofquarterly monitoring should be requiredwith a provision for more frequenttesting to address source water qualityevents. EPA believes that Step 2 testingfrequency should be related to seasonaland other variations in source waterquality as these variations mayinfluence the amount of TOC removalthe treatment plant can achieve.Accordingly, EPA recommends thatsystems utilizing the Step 2 procedurefor compliance perform Step 2 testingquarterly for one year after the effectivedata of the rule. The system may thenapply to the State to reduce testing to aminimum of once per year. If the Statedoes not approve the request forreduced testing frequency, the systemmust continue to test quarterly.


E. Predisinfection Disinfection Credit

1. Today’s RuleToday’s rule does not impose any

constraints on the ability of systems topractice predisinfection and takemicrobial inactivation credit forpredisinfection to meet the disinfectionrequirements of the SWTR. Utilities arefree to take disinfection credit forpredisinfection, regardless of thedisinfectant used, for disinfection thatoccurs after the last point the sourcewater is subject to surface water run-offand prior to the first customer.

2. Background and AnalysisThe 1994 proposed Stage 1 DBPR

(EPA,1994a) discouraged the use ofdisinfectants prior to precursor(measured as TOC) removal by notallowing compliance credit for theSWTR’s disinfection requirements to betaken prior to removal of a specifiedpercentage of TOC. The proposedIESWTR options were intended toinclude microbial treatmentrequirements to prevent increases inmicrobial risk due to the loss ofpredisinfection credit. These optionswere to be implemented simultaneouslywith the Stage 1 DBPR. The purpose ofnot allowing predisinfection credit wasto maximize removal of organicprecursors (measured as TOC) prior tothe addition of a disinfectant, thuslowering the formation of DBPs.

Many drinking water systems usepreoxidation to control a variety ofwater quality problems such as iron andmanganese, sulfides, zebra mussels,Asiatic clams, and taste and odor. The1994 proposed rule did not preclude thecontinuous addition of oxidants tocontrol these problems. However, theproposed regulation, except under a fewspecific conditions, did not allow creditfor compliance with disinfectionrequirements prior to TOC removal.Analysis supporting the proposed ruleconcluded that many plants would beable to comply with the Stage 1 MCLsfor THMs and HAA5 of 0.080 mg/L and0.060 mg/L, respectively, by reductionsin DBP levels as a result of reduceddisinfection practice in the early stagesof treatment. Also, enhancedcoagulation and enhanced softeningwere thought to lower the formation ofother unidentified DBPs as well. The1994 proposal assumed that addition ofdisinfectant prior to TOC removalwould initiate DBP formation throughcontact of the chlorine with the TOC,effectively eliminating the value ofenhanced coagulation for DBPreduction. Finally, the analysisunderlying the 1994 proposedelimination of the preoxidation credit

assumed that the addition ofdisinfectant was essentially ‘‘mutuallyexclusive’’ to the goal of reducing DBPformation by the removal of TOC. Asdiscussed below, new data developedsince 1994 suggest this may not be thecase.

Reasons for Disinfectant Use. In orderto obtain information on the impact thatdisallowing predisinfection would haveon utilities’ disinfection practices, asurvey was sent out to ICR utilities toobtain information on their currentpredisinfection practices. The results ofthe survey of 329 surface watertreatment plants indicated that 80percent (263) of these plants usepredisinfection for one or more reasons.The survey indicated that the majorityof the plants using predisinfection weredoing so for multiple reasons. However,the main reason reported forpredisinfection was microbialinactivation. Algae control, taste andodor control, and inorganic oxidation,in that order, were the next mostfrequently cited reasons for practicingpredisinfection. Seventy-seven percentof plants that predisinfected reportedthat their current levels of Giardialamblia inactivation would be loweredif predisinfection was discontinued andno subsequent additional disinfectionwas added to compensate for change inpractice. Eighty-one percent of plantsthat predisinfected would have to makemajor capital investments to make upfor the lost logs of Giardia lambliainactivation. For example, to maintainthe same level of microbial protectioncurrently afforded, construction toprovide for additional contact time oruse of a different disinfectant might beneeded if predisinfection credit waseliminated.

In addition to the ICR mail survey,results from EPA’s ComprehensivePerformance Evaluations (CPE) from 307PWSs (4 to 750 mgd) reported that 71%of the total number of plants usedpredisinfection and 93% of those thatpredisinfected used two or threedisinfectant application points duringtreatment.

Based on the above information, EPAbelieves that predisinfection is used bya majority of PWSs for microbialinactivation, as well as other drinkingwater treatment objectives. Therefore,disallowing predisinfection credit couldinfluence systems to make changes intreatment to comply with thedisinfection requirements of the SWTRor to maintain current levels ofmicrobial inactivation.

Impact of Point of Chlorination onDBP Formation. The results of a studyby Summers et al. (1997) indicate thatpracticing enhanced coagulation, while

simultaneously maintainingprechlorination, can still result indecreased DBP formation (especially forTOX and TTHM). Greater benefits arerealized by moving the point ofchlorination to post-rapid mixing orfurther downstream for HAA5 control,and to mid-flocculation or post-sedimentation for TOX and TTHMcontrol. These data show that theassumption made in the 1994 proposal,namely that application of anydisinfectant prior to TOC removalwould critically effect DBP formation,was not accurate. The data indicate thatsimultaneous employment of enhancedcoagulation and predisinfection doesnot necessarily mean that DBPformation cannot be substantiallycontrolled (see EPA 1997b for detailedanalysis).

Impact on Softening Plants. In orderto obtain additional information on thecurrent TOC removals being achievedby softening plants, a survey was sent toall the ICR softening utilities (49 plants)requesting that they fill out a single pageof information with yearly average,maximum and minimum values formultiple operating parameters for eachsoftening plant. The survey showed thatin spite of the fact that 78 percent ofsoftening plants are using free chlorinefor at least a portion of theirdisinfection, 90 percent of plants arecurrently meeting an 80 µg/L MCL levelfor TTHMS. All the softening plantsreported average HAA5 levels below 60µg/L. Without predisinfection credit,these plants may have to providedisinfection contact time aftersedimentation, which could meansignificantly increasing the free chlorinecontact time to make up for a shorteneddetention time.

3. Summary of Comments

Most commenters stated that theproposed elimination of predisinfectionwould result in many plants not beingable to maintain existing levels ofdisinfection or comply with the SWTRdisinfection requirements withoutmaking significant compensatorychanges in their disinfection practice.Commenters were concerned thatwithout predisinfection the level ofmicrobial risk their customers wereexposed to could significantly increase,and that eliminating microbialinactivation credit for predisinfection tocomply with the SWTR might influenceutilities to abandon predisinfection tomore easily comply with the TTHM andHAA5 MCLs. EPA agrees with thisconcern and therefore the final rule hasbeen modified from the proposal toallow predisinfection credit.


F. Requirements for Systems to UseQualified Operators

EPA believes that systems that mustmake treatment changes to comply withrequirements to reduce themicrobiological risks and risks fromdisinfectants and disinfectionbyproducts should be operated bypersonnel who are qualified torecognize and react to problems.Therefore, in today’s rule, the Agency isrequiring that all systems regulatedunder this rule be operated by anindividual who meets State specifiedqualifications, which may differ basedon size and type of the system. SubpartH systems already are required to beoperated by qualified operators underthe provisions of the SWTR (40 CFR141.70(c)). Current qualification orcertification programs developed by theStates should, in many cases, beadequate to meet this requirement forSubpart H systems. Also, States mustmaintain a register of qualifiedoperators.

EPA encourages States which do notalready have operator certificationprograms in effect to develop suchprograms. The Reg. Neg. Committee andTWG believed that properly trainedpersonnel are essential to ensure saferdrinking water. States with existingoperator certification programs maywish to update their programs forqualifying operators under the SWTR. Inthese cases, States may wish to indicatethat their operator certificationprograms are being developed inaccordance with EPA’s new guidelines.

G. Analytical Methods

1. Today’s RuleChlorine (Free, Combined, and Total).

Today’s rule approves four methods formeasuring free, combined, and totalchlorine to determine compliance withthe chlorine MRDL (using either free ortotal chlorine) and chloramines MRDL(using either combined or totalchlorine): ASTM Method D1253–86(ASTM, 1996), Standard Methods 4500–Cl D (APHA, 1995), 4500–Cl F (APHA,1995), and 4500–Cl G (APHA, 1995).Additionally, this rule approves twomethods for measuring total chlorine todetermine compliance with the chlorineMRDL and chloramines MRDL:Standard Methods 4500–Cl E (APHA,1995) and 4500–Cl I (APHA, 1995). Therule also contains an additional methodfor measuring free chlorine to determinecompliance with the chlorine MRDL:Standard Method 4500–Cl H (APHA,1995).

Chlorine Dioxide. Today’s ruleapproves two methods for determiningcompliance with the chlorine dioxide

MRDL: Standard Methods 4500–ClO2 D(APHA, 1995) and 4500–ClO2 E (APHA1995). EPA did not approve StandardMethod 4500–ClO2 C (APHA, 1995),which was included in the 1994proposed rule. The Agency determined,in concurrence with the majority ofcommenters on this issue, that StandardMethod 4500–ClO2 C is outdated andinaccurate in comparison to chlorinedioxide methods approved in today’srule and is inadequate for compliancemonitoring.

TTHM. Today’s rule approves threemethods for determining compliancewith the TTHM MCL: EPA Methods502.2 (EPA, 1995), 524.2 (EPA, 1995),and 551.1 (EPA, 1995).

HAA5. Today’s rule approves threemethods for determining compliancewith the HAA5 MCL: EPA Methods552.1 (EPA, 1992) and 552.2 (EPA,1995) and Standard Method 6251B(APHA, 1995).

Bromate. Today’s rule approves amethod for determining compliancewith the bromate MCL: EPA Method300.1 (EPA, 1997e). EPA hasdemonstrated this method to be capableof quantifying bromate at the MCL of 10µg/L under a wide range of solutionconditions. EPA did not approve EPAMethod 300.0 (EPA, 1993b) for bromateanalysis, although this method wasincluded for analysis of bromate in the1994 proposed rule. As stated in theproposed rule, EPA Method 300.0 is notsensitive enough to measure bromate atthe MCL established in today’s rule.EPA Method 300.1 was developedsubsequent to the proposed rule in orderto provide a method with adequatesensitivity to assess bromatecompliance.

Chlorite. Today’s rule approves twomethods for determining compliancewith the chlorite MCL: EPA Methods300.0 (EPA, 1993b) and 300.1 (EPA,1997e). As described elsewhere intoday’s rule, chlorite complianceanalyses are made on samples taken inthe distribution system during monthlymonitoring, or during additionaldistribution system monitoring asrequired. Today’s rule establishes thefollowing method for daily monitoringof chlorite: Standard Method 4500-ClO2

E (APHA, 1995), amperometric titration.As stated elsewhere in today’s rule,daily monitoring of chlorite isconducted on samples taken at theentrance to the distribution system.Commenters supported the use ofamperometric titration as a feasiblemethod for daily monitoring of chlorite.

TOC. Today’s Rule approves threemethods for TOC analysis: StandardMethods 5310 B, 5310 C, and 5310 D,as published in the Standard Methods

19th Edition Supplement (APHA, 1996).EPA believes that all of these methodscan achieve the precision and detectionlevel necessary for compliancedeterminations required in today’s rulewhen the quality control (QC)procedures contained in the methoddescriptions and this rule are followed.However, while any of these methodsmay be used, EPA advises that aconsistent method be employed for allmeasurements in order to reduce theimpact of possible instrument bias.

In accordance with the concerns ofcommenters, today’s rule requirescertain QC procedures for TOC analysesin addition to those contained in themethod descriptions. These additionalQC steps are designed to increase theintegrity of the analysis and have beenfound to be effective in data collectionunder the ICR. Filtration of samplesprior to TOC analysis is not permitted,as this could result in removal oforganic carbon. Where turbidityinterferes with TOC analysis, samplesshould be homogenized and, ifnecessary, diluted with organic-freereagent water. TOC samples must eitherbe analyzed or must be acidified toachieve pH less than 2.0 by minimaladdition of phosphoric or sulfuric acidas soon as practical after sampling, notto exceed 24 hours. Samples must beanalyzed within 28 days.

SUVA (Specific UltravioletAbsorbance). Today’s rule establishesSUVA as an alternative criterion fordemonstrating compliance with TOCremoval requirements contained intoday’s rule. SUVA is a calculatedparameter defined as the UV absorptionat 254 nm (UV254) (measured as m¥1)divided by the DOC concentration(measured as mg/L). If the UVabsorption is first determined in units ofcm¥1, the SUVA equation is multipliedby 100 to convert to m¥1, as shownbelow:SUVA = 100 (cm/m) [UV254 (cm¥1)/DOC

(mg/L)]Two separate analytical methods are

necessary to make this measurement:UV254 and DOC. Today’s rule approvesthree methods for DOC analysis:Standard Methods 5310 B, 5310 C, and5310 D, as published in the StandardMethods 19th Edition Supplement(APHA, 1996); and approves StandardMethod 5910 B (APHA, 1995) for UV254

analysis.The final rule contains QC steps for

the SUVA analyses that are required inaddition to those mandated in themethod descriptions. Theserequirements were developed inresponse to comments solicited by EPAin the 1997 DBP NODA (EPA, 1997b)and are as follows:


—sample acquisition (DOC and UV254

samples used to determine a SUVAvalue must be taken at the same timeand at the same location. SUVA mustbe determined on water prior to theaddition of disinfectants/oxidants.)

—sample preservation (DOC samplesmust either be analyzed or must beacidified to achieve pH less than 2.0by minimal addition of phosphoric orsulfuric acid as soon as practical aftersampling, not to exceed 48 hours. ThepH of UV254 samples may not beadjusted.)

—holding times (DOC samples must beanalyzed within 28 days of sampling.UV254 samples must be analyzed as

soon as practical after sampling, notto exceed 48 hours.)

—filtration (Prior to analysis, UV254 andDOC samples must be filtered througha 0.45 µm pore-diameter filter. DOCsamples must be filtered prior toacidification.)

—background concentrations in thefiltered blanks (Water passed throughthe filter prior to filtration of thesample must serve as the filteredblank. This filtered blank must beanalyzed using procedures identicalto those used for analysis of thesamples and must meet the followingcriteria: TOC <0.5 mg/L.)

Bromide. Today’s rule approves thefollowing two methods for monitoringbromide: EPA Methods 300.0 (EPA,1993b) and 300.1 (EPA, 1997e).

Alkalinity. Today’s rule approvesthree methods for measuring alkalinity:ASTM Method D1067–92B (ASTM,1994), Standard Method 2320 B (APHA,1995), and Method I–1030–85 (USGS,1989).

pH. Today’s rule requires the use ofmethods that have been previouslyapproved in § 141.23(k) formeasurement of pH.

Approved analytical methods aresummarized in Table III–2.

TABLE III–2.—APPROVED ANALYTICAL METHODS

Analyte EPA method Standard method Other

Chlorine (free, combined, total) ................................................................................... ........................ 4500–Cl D ASTM D1253–8......................... 4500–Cl F........................ 4500–Cl G

(Total) .......................................................................................................................... ........................ 4500–Cl E........................ 4500–Cl I

(Free) ........................................................................................................................... ........................ 4500–Cl HChlorine Dioxide .......................................................................................................... ........................ 4500–ClO2 D

........................ 4500–ClO2 ETTHM ........................................................................................................................... 502.2

524.2551.1

HAA5 ........................................................................................................................... 552.1 625l B552.2

Bromate ....................................................................................................................... 300.1Chlorite (monthly) ........................................................................................................ 300.0

300.1(Daily) .......................................................................................................................... ........................ 4500–ClO2 ETOC/DOC .................................................................................................................... ........................ 5310 B

........................ 5310 C

........................ 5310 DUV254 ............................................................................................................................ ........................ 5910 BBromide ....................................................................................................................... 300.0

300.1Alkalinity ....................................................................................................................... ........................ 2320 B ASTM D1067–

92B.USGS I–1030–

85.pH ................................................................................................................................ 150.1 4500–H+B ASTM D1293–84.

150.2

2. Background and Analysis

Chlorine (Free, Combined, and Total).In the 1994 proposed rule, EPAincluded all Standard Methods foranalysis of free, combined, and totalchlorine that were approved in today’srule.

Chlorine Dioxide. The 1994 proposedrule included the same three methodsfor analyzing chlorine dioxide (ClO2)that are approved under the SWTR andICR regulations. Two of these methods,Standard Methods 4500.ClO2 C (APHA,1992) and 4500.ClO2 E (APHA, 1992),are amperometric methods. The thirdproposed method was Standard Method4500.ClO2 D (APHA, 1992), acolorimetric test using the color

indicator N,N-diethyl-p-phenylenediamine (DPD).

TTHM. The 1994 proposed ruleincluded three methods for the analysisof TTHMs. They were EPA Methods502.2, 524.2, and 551. In 1995, EPAMethod 551 was revised to EPA Method551.1, rev. 1.0 (EPA, 1995), which wasapproved for ICR monitoring under 40CFR 141.142.

EPA Method 551.1 has severalimprovements upon EPA Method 551.The use of sodium sulfate is stronglyrecommended over sodium chloride forthe MTBE extraction of DBPs. Thischange was in response to a reportindicating elevated recoveries of somebrominated DBPs due to bromide

impurities in the sodium chloride (Xie,1995). Other changes to EPA Method551.1 include a buffer addition tostabilize chloral hydrate, elimination ofthe preservative ascorbic acid, andmodification of the extraction procedureto minimize the loss of volatile analytes.The revised method requires the use ofsurrogate and other quality controlstandards to improve the precision andaccuracy of the method.

HAA5. The 1994 proposed ruleincluded two methods for the analysisof five haloacetic acids—EPA Method552.1 (EPA, 1992) and Standard Method6233B (APHA, 1992). Both methods usecapillary column gas chromatographsequipped with electron capture


detectors. The two methods differ in thesample preparation steps. EPA Method552.1 uses solid phase extraction disksfollowed by an acidic methanolderivitization. Standard Method 6233Bis a small volume liquid-liquid (micro)extraction with methyl-t-butyl ether,followed by a diazomethanederivitization. Following the proposedrule, Standard Method 6233B wasrevised and renumbered 6251B (APHA,1995) to include bromochloroaceticacid, for which a standard was notcommercially available in 1994.Recognizing these improvements, EPAapproved Standard Method 6251B foranalysis under the ICR (40 CFR Part 141or EPA, 1996a). Several commentersrequested that the revised andrenumbered method, Standard Method6251B, also be approved for the analysisof haloacetic acids under the Stage 1DBPR.

In 1995 EPA published a thirdmethod for HAAs, EPA Method 552.2(EPA, 1995), and subsequently approvedit for HAA analysis under the 1996 ICR(40 CFR Part 141 or EPA, 1996a). EPAMethod 552.2 is an improved method,combining the micro extractionprocedure of Standard Method 6233Bwith the acidic methanol derivitizationprocedure of EPA Method 552.1. It iscapable of analyzing nine HAAs.

Bromate. The 1994 proposed rulerequired systems that use ozone tomonitor for bromate ion. EPA proposedEPA Method 300.0 (EPA, 1993b) for theanalysis of bromate and chlorite ions.However, at the time of the proposal,EPA was aware that EPA Method 300.0was not sensitive enough to measurebromate ion concentration at theproposed MCL of 10 µg/L. EPArecognized that modifications to themethod would be necessary to increasethe method sensitivity. Studies at thattime indicated that changes to theinjection volume and the eluentchemistry would decrease the detectionlimit below the MCL. Many commentersto the 1994 proposal agreed that EPAMethod 300.0 was not sensitive enoughto determine compliance with a MCL of10 µg/L bromate ion, given that MCLsare typically set at 5 times the minimumdetection levels (MDLs).

Following the proposal, EPAimproved EPA Method 300.0 andrenumbered it as EPA Method 300.1(EPA, 1997b). EPA Method 300.1specifies a new, high capacity ionchromatography (IC) column that isused for the analysis of all anions listedin the method, instead of requiring twodifferent columns as specified in EPAMethod 300.0. The new column has ahigher ion exchange capacity thatimproves chromatographic resolution

and minimizes the potential forchromatographic interferences fromcommon anions at concentrations10,000 times greater than bromate ion.For example, quantification of 5.0 µg/Lbromate is feasible in a matrixcontaining 50 mg/L chloride.Minimizing the interferences permitsthe introduction of a larger samplevolume to yield method detection limitsin the range of 1–2 µg/L.

In the 1997 DBPR NODA (EPA,1997b), EPA discussed EPA Method300.1 and projected that by using itlaboratories would be able to quantifybromate with the accuracy andprecision necessary for compliancedetermination with an MCL of 10 µg/L.Although there would be a limitednumber of laboratories that would bequalified to do such analyses, EPAdetermined that there should beadequate laboratory capacity forbromate ion compliance monitoring bythe time the rule becomes effective.

Chlorite. The proposed rule requiredsystems using chlorine dioxide fordisinfection or oxidation to performmonthly monitoring for chlorite ion inthe distribution system. EPA designatedEPA Method 300.0 (ionchromatography) for chlorite analysis.EPA considered other methods usingamperometric and potentiometrictechniques but decided that only the ionchromatography method (EPA Method300.0) would produce results with theaccuracy and precision needed fordetermining compliance. Subsequent tothe proposed rule, EPA Method 300.0was improved in order to achieve lowerdetection limits for bromate ion andrenumbered as EPA Method 300.1.

TOC. To satisfy requirements of theStage 1 DBPR, the 1994 proposed ruledirected that a TOC analytical methodshould have a detection limit of at least0.5 mg/L and a reproducibility of ± 0.1mg/L over a range of 2 to 5 mg/L TOC.The proposed rule included twomethods for analyzing TOC: StandardMethods 5310 C, which is thepersulfate-ultraviolet oxidation method,and 5310 D, the wet-oxidation method(APHA, 1992). These methods wereselected because, according to datapublished in Standard Methods (APHA1992), they could achieve the necessaryprecision and detection limit. StandardMethod 5310 B, the high-temperaturecombustion method, was considered butnot proposed because it was describedin Standard Methods (1992, APHA) ashaving a detection limit of 1 mg/L. Theproposal stated that if plannedimprovements to the instrumentationused in Standard Method 5310 B weresuccessful, the next version would beconsidered for promulgation. Revisions

of Standard Methods 5310 B, C, and Dwere published in Standard Methods19th Edition Supplement (APHA, 1996).The revised version of Standard Method5310 B recognized the capacity ofcertain high temperature instruments toachieve detection limits below 1 mg/Lusing this method.

SUVA (Specific UltravioletAbsorbance). SUVA analytical methodswere not addressed in the 1994proposed rule because SUVA had notbeen developed and proposed as acompliance parameter for TOC removalrequirements at that time. The analyticalmethods and associated QC proceduresfor DOC and UV254 approved in today’srule are those on which the Agencysolicited comment in the 1997 DBPRNODA (EPA, 1997b).

Bromide. The 1994 proposed ruleincluded EPA Method 300.0 for analysisof bromide. EPA believed that theworking range of this methodadequately covered the requirementsproposed for bromide monitoring. Asdescribed above, EPA developedMethod 300.1 for improved bromateanalysis subsequent to the proposedrule. EPA Method 300.1 can alsoeffectively measure bromide at theconcentration of 50 µg/L, required intoday’s rule for reduced monitoring ofbromate.

Alkalinity. The proposed ruleincluded all methods approved by EPAfor measuring alkalinity. These methodshave all been approved in today’s rule.

3. Summary of CommentsFollowing is a discussion of major

comments on the analytical methodsrequirements of the Stage 1 DBPR.

Chlorine. A commenter to the 1994proposal recommended approval ofASTM method D1253–86. EPAdetermined that this method isequivalent to Standard Method 4500–ClD, and has approved this method intoday’s rule.

Chlorine Dioxide. EPA receivedcomments on the proposed ruledetailing weaknesses of the methodsselected to calculate ClO2. Commenterspointed out that other halogenatedspecies, such as free chlorine,chloramines, and chlorite, as well ascommon metal ions (e.g. copper,manganese, chromate) will interferewith these methods. Additionally,where these methods determineconcentrations by difference, they arepotentially inaccurate and subject topropagation of errors. Commentersspecifically criticized Standard Method4500–ClO2 C (APHA 1995),amperometric method I, which wascharacterized as outdated andinaccurate, and stated that Standard


Method 4500–ClO2 E (APHA 1995),amperometric method II, is asubstantially better method.Consequently, in the 1997 DBP NODA,EPA requested comment on removingStandard Method 4500–ClO2 C from thelist of approved methods for theanalysis of chlorine dioxide forcompliance with the MRDL.

Comments on the 1997 DBPR NODAfavored eliminating Standard Method4500.ClO2 C as an approved method forClO2 compliance analysis. EPA does notapprove this method in today’s rule.EPA recognizes that the two methodsapproved for ClO2 monitoring undertoday’s rule are subject to interferences.However, EPA believes that thesemethods can be used effectively toindicate compliance with the ClO2

MRDL when the quality controlprocedures contained in the methoddescriptions are followed. Severalcommenters also encouraged EPA toapprove a more sensitive and specificmethod for ClO2 analysis, and suggestedalternative methods including AcidChrome Violet K, Lissamine Green B,and Chlorophenol Red. While EPAsupports the development of improvedanalytical methods for chlorine dioxide,the Agency believes that at this time themethods suggested by commenters havenot gone through the necessaryperformance validation processes towarrant their approval for compliancemonitoring.

Bromate. In the 1994 proposed rule,EPA discussed the fact that the currentversion of EPA Method 300.0 was notsensitive enough to measure bromateion concentrations at the proposed MCLand requested comment onmodifications to EPA Method 300.0 toimprove its sensitivity. In the 1997NODA, EPA presented EPA Method300.1 and requested comment onreplacing EPA Method 300.0 with EPAMethod 300.1 for the analysis ofbromate.

Commenters agreed that EPA Method300.1 is a more sensitive method thanEPA Method 300.0 for low level bromateanalysis and the majority suggested thatEPA Method 300.1 be the approvedmethod for bromate analysis. Onecommenter requested thatinterlaboratory round-robin testing beconducted before EPA Method 300.1 isaccepted for Stage 1 DBPR compliancemonitoring. EPA considersinterlaboratory round-robin testing ofEPA Method 300.1 to be unnecessarybecause this method is essentially animprovement of EPA Method 300.0which is already approved. EPA Method300.1 primarily makes use of a superioranalytical column to achieve increasedsensitivity for bromate analysis.

Moreover, the efficacy of EPA Method300.1 in a wide range of samplematrices is demonstrated by theperformance validation data containedin the published method description.Based on a review of all the publiccomments, EPA is approving EPAMethod 300.1 for bromate analysis intoday’s rule.

Chlorite. EPA solicited comment inthe 1997 DBPR NODA on approvingEPA Method 300.1, in addition to EPAMethod 300.0, for compliance analysisof chlorite. The majority of commenterson this issue favored approval of bothmethods and today’s rule establishesboth for determining compliance withthe chlorite MCL.

In the 1994 proposed rule, EPArequested comment on changingmonitoring requirements for chlorite toreflect concern about potential acutehealth effects. Several commentersstated that daily monitoring of chloritewould be feasible if an amperometricanalytical method could be used.Commenters suggested that dailyamperometric analyses for chlorite beconducted on samples taken from theentrance to the distribution system, andthat weekly or monthly analyses usingion chromatography still be required asa check, because ion chromatography isa more accurate analytical method.Commenters noted that dailymonitoring for chlorite would provideimproved operational control of plantsand reduce the likelihood of systemsincurring compliance violations.

Today’s rule establishes amperometrictitration (Standard Method 4500–ClO2

E) for daily analyses of chlorite samplestaken at the entrance to the distributionsystem, along with monthly (orquarterly if reduced, or additional asrequired), analyses by ionchromatography (EPA Methods 300.0and 300.1) of chlorite samples takenfrom within the distribution system.EPA believes that the ionchromatography method, rather than theamperometric method, should be usedfor making chlorite compliancedeterminations in the distributionsystem due to its greater accuracy.However, the amperometric method issufficient for the purposes of dailymonitoring at the entrance to thedistribution system, which are tosignificantly aid in proper operationalcontrol of a treatment plant and toindicate when distribution systemtesting is appropriate. For this reason,only the ion chromatographic methods(EPA Method 300.0 and 300.1), and notthe amperometric titration methods, areapproved in today’s rule for determiningcompliance with the chlorite MCL.

A minority of commenters on thisissue suggested that the DPD method(Standard Method 4500–ClO2 D (APHA1995)) be approved for daily monitoringof chlorite ion levels. EPA hasdetermined that the accuracy andprecision of the DPD method (StandardMethod 4500–ClO2 D) in themeasurement of chlorite aresubstantially worse than with StandardMethod 4500–ClO2 E, and areinsufficient for this method to be usedfor daily monitoring of chlorite. As aconsequence, EPA has not approved theDPD method for chlorite monitoring intoday’s rule.

TOC. EPA received several commentson the 1994 proposal requestingapproval of Standard Method 5310 B forTOC compliance analysis. Commentersstated that newer instrumentation couldachieve a detection limit of 0.5 mg/LTOC using this method. Following thepublication of a revised version ofMethod 5310 B in Standard Methods19th Edition Supplement (APHA 1996)which recognized the capacity of somecombustion based TOC analyzers toachieve detection limits below 1 mg/L,EPA requested comment on approvingStandard Method 5310 B, along withStandard Methods 5310 C and 5310 D,for the analysis of TOC in the 1997DBPR NODA.

The majority of commenters on TOCanalysis urged EPA to approve all threemethods. Commenters were concerned,though, that because these threemethods employ different processes tooxidize organic carbon to carbondioxide, results from different TOCanalyzers could vary to a degree that isof regulatory significance. Specifically,the efficiency of oxidation of largeorganic particles or very large organicmolecules such as tannins, lignins, andhumic acids may be lower withpersulfate based instruments (APHA1996). Although available datacomparing different TOC methods islimited, one study observed a persulfatecatalytic oxidation technique tounderestimate the TOC concentrationmeasured by a high temperaturecatalytic oxidation technique by 3–6%on stream water and soil water samples(Kaplan, 1992). Standard Methodsrecommends checking the oxidationefficiency of the instrument with modelcompounds representative of the samplematrix, because many factors caninfluence conversion of organic carbonto carbon dioxide (APHA 1996).

EPA believes that the potentialregulatory impact of small disparities inoxidation efficiencies between differentTOC analyzers is minor. Studies usingPE samples indicate that for instrumentscalibrated in accordance with the


procedures specified in StandardMethods (APHA, 1996), the magnitudeof measurement error due to analyticaldiscrepancies between instruments willtypically be less than the measurementuncertainty attributed to a particularinstrument (EPA, 1994c). In addition,EPA anticipates that most systems willuse a consistent method for TOCanalyses and that this will assist inminimizing the importance ofinstrument bias. This practice wassuggested by several commenters.

Commenters also suggested that EPAimplement a formal certification processfor laboratories measuring TOC. Somecommenters recommended that EPArequire a laboratory approval process forTOC measurements under the Stage 1DBPR that is similar to what is requiredunder the ICR. EPA requires that TOCanalyses be conducted by a partyapproved by EPA or the State but notthat TOC measurements be subject tothe same laboratory certificationprocedures required for the analysis ofDBPs. However, today’s rule containsQC requirements for TOC analyseswhich are in addition to those inStandard Methods. These additional QCprocedures pertain to samplepreservation and holding time, and havebeen found to be effective for TOCanalyses under the ICR.

SUVA. In the 1997 DBPR NODA, EPAsolicited comment on a range of issuesdealing with the determination of SUVAincluding: analytical methods,sampling, sample preparation, filtertypes, pH, interferences to UV, highturbidity waters, quality control, andother issues that should be addressed.The Agency requested comment onapproving Standard Method 5910 B formeasuring UV254 and Standard Methods5310 B, C, and D, for measuring DOC.In requesting comment on filtration,EPA noted that filtration is necessaryprior to both UV254 and DOC analyses inorder to eliminate particulate matter andseparate the operationally defineddissolved organic matter (based on a0.45 µm-pore-diameter cut-off).However, filtration can also corruptsamples through adsorption ofcarbonaceous material onto the filter orits desorption from it (APHA 1996). Inaddition, EPA requested comment onrequiring that UV254 and DOC analysesbe measured from the same samplefiltrate.

The majority of commenters on SUVAanalytical methods recommended thatEPA approve Standard Methods 5310 B,C, and D, for DOC analysis and StandardMethod 5910 B for UV254 analysis. EPAhas approved these methods in today’srule. In addition, commenters stressedthe importance of sample preparation,

especially filtration, in the measurementof DOC and observed that sufficientwashing of filters prior to filtration ofsamples is critical to preventingcontamination of the samples by organiccarbon from the filters. Severalcomments on the 1997 DBPR NODAexpressed opposition to a requirementthat UV254 and DOC analyses be madeon the same sample filtrate.Commenters stated that this isimpractical because UV analyses areoften conducted at the treatment plantwhile DOC analyses are typically runoff-site. Commenters also noted thatDOC samples should be acid preservedwhereas pH adjustment of samples forUV254 analysis is improper.

Today’s rule establishes that samplesfor DOC and UV254 analyses must befiltered through a 0.45 µm-pore-diameter filter. EPA does not havespecific requirements on the type offilter that is used, provided it has a 0.45µm pore-diameter, but will provideguidance on this issue in the GuidanceManual for Enhanced Coagulation. Thismanual will be available for publicreview after promulgation of the Stage 1DBPR. Today’s rule addresses filterwashing prior to analysis by requiringthat water passed through the filter priorto filtration of the sample serve as thefiltered blank. The filtered blank mustbe analyzed using procedures identicalto those used for analysis of the samplesand must meet the following criteria:TOC < 0.5 mg/L. These criteria are themaximum allowable backgroundconcentrations specified for theseanalyses under the ICR. In the GuidanceManual for Enhanced Coagulation, EPAwill furnish instructions on samplehandling and filter washing to assistsystems in achieving acceptable fieldreagent blanks.

Filtration of samples for DOC analysismust be done prior to acid preservation,as stipulated in today’s rule. This isnecessary because acidification of thesample to pH < 2 can cause substantialprecipitation of dissolved organicspecies. Because biological activity willrapidly alter the DOC of a sample thathas not been preserved, EPA requiresthat DOC samples be acidified to pH <2.0 within 48 hours of sampling.Consequently, filtration of DOC samplesmust be done within 48 hours in orderto allow acid preservation within thistime period. The pH of UV254 samplesmay not be adjusted. Today’s rule placesa maximum holding time from samplingto analysis of 2 days for UV254 samplesand 28 days for DOC samples. Theseholding times are the same as thoseapproved for ICR data collection.

Because the filtration procedures forUV254 and DOC samples are largely

identical, EPA anticipates that mostsystems will find it economical whendetermining SUVA to filter one sample.The filtrate would then be split into twoportions, one of which would be usedfor UV analysis while the other wouldbe acid preserved and used for DOCanalysis. However, EPA has notincluded a requirement that the DOCand UV254 analyses used in the SUVAdetermination be made on the samesample filtrate. Instead, EPA requiresthat DOC and UV254 samples used todetermine a SUVA value must be takenat the same time and at the samelocation.

In the 1997 DBPR NODA, EPA alsoobserved that because disinfectants/oxidants (chlorine, ozone, chlorinedioxide, potassium permanganate)typically reduce UV254 withoutsubstantially impacting DOC, raw waterSUVA should be determined on waterprior to the application of disinfectants/oxidants. If disinfectants/oxidants areapplied in raw-water transmission linesupstream of the plant, then raw waterSUVA should be based on a samplecollected upstream of the point ofdisinfectant/oxidant addition. Fordetermining settled-water SUVA, if theplant applies disinfectants/oxidantsprior to the settled water sample tap,then settled-water SUVA should bedetermined in jar testing. Nocommenters were opposed to theseprovisions and today’s rule requires thatsamples used for SUVA determinationsbe taken from water prior to theaddition of any oxidants/disinfectants.

A few commenters stated that SUVAshould not be subject to rigorousanalytical procedures because theapplication of SUVA in this rule isbased on a relationship which is largelyempirical (i.e. correlations betweenSUVA and TOC removal bycoagulation). EPA recognizes theempirical nature of this relationship andthe variance it has displayed in studies.Regulations, however, must addressspecific SUVA values if SUVA is toserve as an alternative complianceparameter. For compliance with theseregulations to be meaningful, SUVAmust be determined accurately.Consequently, today’s rule requirescertain QC procedures in the DOC andUV254 analyses that are used to calculateSUVA.

Today’s rule establishes the removalof 10 mg/L magnesium hardness (asCaCO3) as an alternative performancecriterion that systems practicingenhanced softening can use todemonstrate compliance with thetreatment technique requirement forTOC removal. However, EPA did notpropose methods for the analysis of


magnesium in drinking water andtherefore the final rule does not containany approved methods for magnesium.EPA expects to propose magnesiumanalytical methods to be used forcompliance monitoring under the Stage1 DBPR by the end of 1998.

4. Performance Based MeasurementSystems

On October 6, 1997, EPA published aDocument of the Agency’s intent toimplement a Performance BasedMeasurement System (PBMS) in all ofits programs to the extent feasible (EPA,1997f). The Agency is currentlydetermining the specifics stepsnecessary to implement PBMS in itsprograms and preparing animplementation plan. Final decisionshave not yet been made concerning theimplementation of PBMS in drinkingwater programs. However, EPA iscurrently evaluating what relevantperformance characteristics should bespecified for monitoring methods usedin the drinking water programs under a

PBMS approach to ensure adequate dataquality. EPA would then specifyperformance requirements in itsregulations to ensure that any methodused for determination of a regulatedanalyte is at least equivalent to theperformance achieved by othercurrently approved methods. EPAexpects to publish its PBMSimplementation strategy for waterprograms in the Federal Register by theend of calendar year 1998.

Once EPA has made its finaldeterminations regardingimplementation of PBMS in programsunder the Safe Drinking Water Act, EPAwould incorporate specific provisions ofPBMS into its regulations, which mayinclude specification of the performancecharacteristics for measurement ofregulated contaminants in the drinkingwater program regulations.

H. Monitoring Requirements

1. Today’s Rule

Today’s rule establishes monitoringrequirements to support implementationof the enhanced coagulation andenhanced softening treatmenttechnique, implementation of newMCLs for TTHM, HAA5, bromate, andchlorite, and implementation of MRDLsfor chlorine, chloramines, and chlorinedioxide. Monitoring for DBPs,disinfectant residuals, and TOC must beconducted during normal operatingconditions. Failure to monitor inaccordance with the monitoring plan isa monitoring violation. Wherecompliance is based on a runningannual average of monthly or quarterlysamples or averages and the system’sfailure to monitor makes it impossible todetermine compliance with MCLs orMRDLs, this failure to monitor will betreated as a violation.

Tables III–3 and III–4 belowsummarize routine and reducedmonitoring requirements of today’s rule.

TABLE III–3.—ROUTINE MONITORING REQUIREMENTS 1

Requirement(reference) Location for sampling Large surface sys-

tems 2Small surface sys-

tems 2Large ground water

systems 3Small ground water

systems 3

TOC and Alkalinity(141.132(d)(1)).

Source Water 4 .......... 1sample/month/plant 3 1 sample/month/plant3.

NA ............................. NA.

Only required forplants with conven-tional filtration treat-ment.

TTHMs and HAA5(141.132(b)(1)(i)).

25% in dist sys atmax res time, 75%at dist sys rep-resentative loca-tions.

4/plant/quarter ........... 1/plant/quarter5 ......... 1/plant/quarter 6 ......... 1/plant/year 5,6

at maximum resi-dence time.



if pop.<500, then 1/plant/yr 8.

during warmestmonth.

during warmestmonth.

Bromate 7

(141.132(b)(3)(i)).Dist sys entrance

point.1/month/trt plant

using O3.1/month/trt plant



using O3.Chlorite8 (daily)

(141.132(b)(2)(i)(A)).Dist sys entrance

point.Daily/trt plant using

CIO2.Daily/trt plant using

CIO2.Daily/trt/plant using

CIO2.Chlorite8 (monthly)

141.132(b)(2)(i)(B)).Dist sys: 1 near first

cust, 1 in dist sysmiddle, 1 at maxres time.

3 sample set/month .. 3 sample set/month .. 3 sample set/month .. 3 sample set/month.

Chlorine andchloramines(141.132(c)(1)(i)).

Same points as totalcoliform in TCR.

Same times as totalcoliform in TCR.




Chlorine dioxide8

(141.132(c)(2)(i)).Dist sys entrance

point.Daily/trt plant using




CIO.

1 Samples must be taken during representative operating conditions. Provisions for reduced monitoring shown elsewhere.2 Large surface (subpart H) systems serve 10,000 or more persons. Small surface (subpart H) systems serve fewer than 10,000 persons.3 Large systems using ground water not under the direct influence of surface water serve 10,000 or more persons. Small systems using

ground water not under the direct influence of surface water serve fewer than 10,000 persons.4 Subpart H systems which use conventional filtration treatment (defined in section 141.2) must monitor 1) source water TOC prior to any treat-

ment and 2) treated TOC at the same time; these two samples are called paired samples. Systems must take a source water alkalinity sample atthe same time.

5 If the annual monitoring result exceeds the MCL, the system must increase monitoring frequency to 1/plant/quarter. Compliance determina-tions will be based on the running annual average of quarterly monitoring results.


6 Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimumnumber of samples.

7 Only required for systems using ozone for oxidation or disinfection.8 Only required for systems using chlorine dioxide for oxidation or disinfection. Additional chlorite monitoring required if daily sample exceeds

MCL. Additional chlorine dioxide monitoring requirements apply if any chlorine dioxide sample exceeds the MRDL.

TABLE III–4.—REDUCED MONITORING REQUIREMENTS 1

Requirement(reference)

Location for reducedsampling Reduced monitoring frequency and prerequisites 2

TOC and Alkalinity(141.132(d)(2)).

Paired samples 3 ......... Subpart H systems-reduced to 1 paired sample/plant/quarter if 1) avg TOC < 2.0 mg/l for 2years or 2) avg TOC < 1.0 mg/l for 1 year.

TTHMs and HAA5s(141.132(b)(1)(ii)).

In dist sys at point withmax res time.

Monitoring cannot be reduced if subpart H system source water TOC > 4.0 mg/l.

Subpart H systems serving 10,000 or more-reduced to 1/plant/qtr if 1) system has completedat least 1 yr of routine monitoring and 2) both TTHM and HAA5 running annual averagesare no more than 40 µg/l and 30 µg/l, respectively.

Subpart H systems serving <10,000 and ground water systems 4 serving 10,000 or more-re-duced to 1/plant/yr if 1) system has completed at least 1 yr of routine monitoring and 2)both TTHM and HAA5 running annual averages are no more than 40 µg/l and 30 µg/l, re-spectively. Samples must be taken during month of warmest water temperature. Subpart Hsystems serving <500 may not reduce monitoring to less than 1/plant/yr.

Groundwater systems 6 serving<10,000-reduced to 1/plant/3yr if 1) system has completed atleast 2 yr of routine monitoring and both TTHM and HAA5 running annual averages are nomore than 40 µg/l and 30 µg/l, respectively or 2) system has completed at least 1 yr ofroutine monitoring and both TTHM and HAA5 annual samples are no more than 20 µg/land 15 µg/l, respectively. Samples must be taken during month of warmest water tempera-ture.

Bromate 5

(141.132(b)(3)(ii)).Dist sys entrance point 1/qtr/trt plant using O3, if system demonstrates 1) avg raw water bromide <0.05 mg/l (based

on annual avg of monthly samples).Chlorite 6

(141.132(b)(2)(iii)).Dist sys: 1 near first

cust, 1 in dist sysmiddle, 1 at max restime.

Systems may reduce routine distribution system monitoring from monthly to quarterly if thechlorite concentration in all samples taken in the distribution system is below 1.0 mg/L for aperiod of one year; 3 samples per quarter.

Chlorine, chlorine diox-ide 6, chloramines(141.132(c)(2)(ii) and(c)(2)(iii).

NA ............................... Monitoring may not be reduced.

1 Samples must be taken during representative operating conditions. Provisions for routine monitoring shown elsewhere.2 Requirements for cancellation of reduced monitoring are found in the regulation.3 Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1) source water TOC prior to any treat-

ment and 2) treated TOC before continuous disinfection (except that systems using ozone followed by biological filtration may sample after bio-logical filtration) at the same time; these two samples are called paired samples.

4 Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimumnumber of samples.

5 Only required for systems using ozone for oxidation or disinfection.6 Only required for systems using chlorine dioxide for oxidation or disinfection.

The formation rate of DBPs is affectedby type and amount of disinfectantused, water temperature, pH, amountand type of precursor material in thewater, and the length of time that waterremains in the treatment anddistribution systems. For this reason,today’s rule specifies the points in thedistribution system (and, in some cases,the time) where samples must be taken.For purposes of this regulation, multiplewells drawing raw water from a singleaquifer may, with State approval, beconsidered one plant for determiningthe minimum number of samples.

TTHM and HAA5. Any system maytake samples in excess of the requiredfrequency. In such cases, at least 25percent of all samples collected eachquarter must be taken at locationswithin the distribution system thatrepresent the maximum residence timeof the water in the system. The

remaining samples must be taken atlocations representative of at leastaverage residence time in thedistribution system.

Subpart H Systems Serving 10,000 orMore People. Routine Monitoring: CWSsand NTNCWSs using surface water (orground water under direct influence ofsurface water) (Subpart H systems) thattreat their water with a chemicaldisinfectant and serve 10,000 or morepeople must routinely take four watersamples each quarter for both TTHMsand HAA5 for each treatment plant inthe system. At least 25 percent of thesamples must be taken at the point ofmaximum residence time in thedistribution system. The remainingsamples must be taken at representativepoints in the distribution system. Thismonitoring frequency is the same as thefrequency required under the currentTTHM rule (§ 141.30).

Reduced Monitoring: To qualify forreduced monitoring, systems must meetcertain prerequisites (see Figure III–1).Systems eligible for reduced monitoringmay reduce the monitoring frequencyfor TTHMs and HAA5 to one sample pertreatment plant per quarter. Systems ona reduced monitoring schedule mayremain on that reduced schedule as longas the average of all samples taken inthe year is no more than 0.060 mg/L forTTHM and 0.045 mg/L for HAA5.Systems that do not meet these levelsmust revert to routine monitoring in thequarter immediately following thequarter in which the system exceeded0.060 mg/L for TTHM or 0.045 mg/L forHAA5. Additionally, the State mayreturn a system to routine monitoring atthe State’s discretion.


FIGURE III–1.—ELIGIBILITY FOR REDUCED TTHM AND HAA5 MONITORING: GROUND WATER SYSTEMS SERVING 10,000OR MORE PEOPLE AND SUBPART H SYSTEMS SERVING 500 OR MORE PEOPLE

Ground water systems serving 10,000 or more people, and Subpart H systems serving 500 or more people, may reduce monitoring of TTHMsand HAA5 if they meet all of the following conditions:

—The annual average for TTHMs is no more than 0.040 mg/L.—The annual average for HAA5 is no more than 0.030 mg/L.—At least one year of routine monitoring has been completed.—Annual average source water TOC level is no more than 4.0 mg/L prior to treatment (applies to Subpart H systems only).

Compliance Determination: A publicwater system (PWS) is in compliancewith the MCL when the running annualarithmetic average of quarterly averagesof all samples, computed quarterly, isless than or equal to the MCL. If therunning annual average computed forany quarter exceeds the MCL, thesystem is out of compliance.

Subpart H Systems Serving 500 to9,999 People. Routine Monitoring:Systems are required to take one watersample each quarter for each treatmentplant in the system. Samples must betaken at the point of maximumresidence time in the distributionsystem.

Reduced Monitoring: To qualify forreduced monitoring, systems must meetcertain prerequisites (see Figure III–1).Systems eligible for reduced monitoringmay reduce the monitoring frequencyfor TTHMs and HAA5 to one sample pertreatment plant per year. Sample mustbe taken at a distribution systemlocation reflecting maximum residencetime and during the month of warmestwater temperature. Systems on areduced monitoring schedule mayremain on that reduced schedule as longas the average of all samples taken inthe year is no more than 0.060 mg/L forTTHM and 0.045 mg/L for HAA5.Systems that do not meet these levelsmust revert to routine monitoring in thequarter immediately following thequarter in which the system exceeded0.060 mg/L for TTHM or 0.045 mg/L forHAA5. Additionally, the State mayreturn a system to routine monitoring atthe State’s discretion.

Compliance Determination: A PWS isin compliance with the MCL for TTHMand HAA5 when the annual average ofall samples, taken that year, is less thanor equal to the MCL. If the average forthese samples exceeds the MCL, thesystem is out of compliance.

Subpart H Systems Serving Fewerthan 500 People. Routine Monitoring:Subpart H systems serving fewer than500 people are required to take onesample per year for each treatment plantin the system. The sample must be takenat the point of maximum residence timein the distribution system during themonth of warmest water temperature. Ifthe annual sample exceeds the MCL, the

system must increase monitoring to onesample per treatment plant per quarter,taken at the point of maximumresidence time in the distributionsystem.

Reduced Monitoring: These systemsmay not reduce monitoring. Systems onincreased monitoring may return toroutine monitoring if the annual averageof quarterly samples is no more than0.060 mg/L for TTHM and 0.045 mg/Lfor HAA5.

Compliance Determination: A PWS isin compliance when the annual sample(or average of annual samples, ifadditional sampling is conducted) isless than or equal to the MCL. If theannual sample exceeds the MCL, thesystem must increase monitoring to onesample per treatment plant per quarter.If the running annual average of thequarterly samples then exceeds theMCL, the system is out of compliance.

Ground Water Systems Serving 10,000or More People. Routine Monitoring:CWSs and NTNCWSs using only groundwater sources not under the directinfluence of surface water that treattheir water with a chemical disinfectantand serve 10,000 or more people arerequired to take one water sample eachquarter for each treatment plant in thesystem. Samples must be taken at pointsthat represent the maximum residencetime in the distribution system.

Reduced Monitoring: To qualify forreduced monitoring, systems must meetcertain prerequisites (see Figure III–1).Systems eligible for reduced monitoringmay reduce the monitoring frequency toone sample per treatment plant per year.Sample must be taken at a distributionsystem location reflecting maximumresidence time and during the month ofwarmest water temperature. Systems ona reduced monitoring schedule mayremain on that reduced schedule as longas the average of all samples taken inthe year is no more than 0.060 mg/L forTTHM and 0.045 mg/L for HAA5.Systems that do not meet these levelsmust revert to routine monitoring in thequarter immediately following thequarter in which the system exceeded0.060 mg/L for TTHM or 0.045 mg/L forHAA5. Additionally, the State mayreturn a system to routine monitoring atthe State’s discretion.

Compliance Determination: A PWS isin compliance with the MCL when therunning arithmetic annual average ofquarterly averages of all samples,computed quarterly, is less than orequal to the MCL. If the running annualaverage for any quarter exceeds theMCL, the system is out of compliance.

Ground Water Systems Serving Fewerthan 10,000 People Routine Monitoring:CWSs and NTNCWSs using only groundwater sources not under the directinfluence of surface water that treattheir water with a chemical disinfectantand serve fewer than 10,000 people arerequired to sample once per year foreach treatment plant in the system. Thesample must be taken at the point ofmaximum residence time in thedistribution system during the month ofwarmest water temperature. If thesample (or the average of annualsamples if more than one sample istaken) exceeds the MCL, the systemmust increase monitoring to one sampleper treatment plant per quarter.

Reduced Monitoring: To qualify forreduced monitoring, systems must meetcertain prerequisites (see Figure III–2).Systems eligible for reduced monitoringmay reduce the monitoring frequencyfor TTHMs and HAA5 to one sample perthree-year monitoring cycle. Samplemust be taken at a distribution systemlocation reflecting maximum residencetime and during the month of warmestwater temperature. Systems on areduced monitoring schedule mayremain on that reduced schedule as longas the average of all samples taken inthe year is no more than 0.060 mg/L forTTHM and 0.045 mg/L for HAA5.Systems that do not meet these levelsmust resume routine monitoring.Systems on increased monitoring mayreturn to routine monitoring if theannual average of quarterly samples isno more than 0.060 mg/L for TTHM and0.045 mg/L for HAA5.

Compliance Determination: A PWS isin compliance when the annual sample(or average of annual samples) is lessthan or equal to the MCL.


FIGURE III–2.—ELIGIBILITY FOR REDUCED TTHM AND HAA5 MONITORING: GROUND WATER SYSTEMS SERVING FEWERTHAN 10,000 PEOPLE

Systems using ground water not under the direct influence of surface water that serve fewer than 10,000 people may reduce monitoring forTTHMs and HAA5 if they meet either of the following conditions:

1. The average of two consecutive annual samples for TTHMs is no more than 0.040 mg/L, the average of two consecutive annual samples forHAA5 is no more than 0.030 mg/L, and at least two years of routine monitoring has been completed.

2. The annual sample for TTHMs is no more than 0.020 mg/L, the annual sample for HAA5 is no more than 0.015 mg/L, and at least one yearof routine monitoring has been completed.

Chlorite. Routine Monitoring: CWSsand NTNCWSs using chlorine dioxidefor disinfection or oxidation arerequired to conduct sampling forchlorite both daily at the entrance to thedistribution system and monthly withinthe distribution system. Additionaldistribution system monitoring may berequired, and distribution systemmonitoring may be reduced if certainconditions are met. This monitoring isdescribed below.

Routine Monthly Monitoring—Systems are required to take a threesample set each month in thedistribution system. One sample mustbe taken at each of the followinglocations: (1) as close as possible to thefirst customer, (2) in a locationrepresentative of average residence time,and (3) as close as possible to the endof the distribution system (reflectingmaximum residence time in thedistribution system). As describedelsewhere in this document, all samplestaken in the distribution system must beanalyzed by ion chromatography(Methods 300.0 and 300.1).

Routine Daily Monitoring—Systemsmust take one sample each day at theentrance to the distribution system. Asdescribed elsewhere in this document(section III.G), samples taken at thedistribution system entrance may beanalyzed by amperometric titration(Method 4500–ClO2 E). If the chloriteMCL is exceeded at the entrance to thedistribution system, the system is notout of compliance. However, the systemmust carry out addition monitoring asdescribed in the following paragraph.

Additional Monitoring: On any daywhen the chlorite concentrationmeasured at the entrance to thedistribution system exceeds the chloriteMCL (1.0 mg/L), the system is requiredto take a three sample set in thedistribution system on the followingday, at the locations specified forroutine monthly monitoring. If thesystem is required to conductdistribution system monitoring as aresult of having exceeded the chloriteMCL at the entrance to the distributionsystem, and the average of the threesamples taken in the distribution systemis below 1.0 mg/L, the system will havesatisfied its routine monthly monitoring

requirement for that month. Furtherdistribution system monitoring will notbe required in that month unless thechlorite concentration at the entrance tothe distribution system again exceeds1.0 mg/L.

Reduced Monitoring: Systems mayreduce routine distribution systemmonitoring for chlorite from monthly toquarterly if the chlorite concentration inall samples taken in the distributionsystem is below 1.0 mg/L for a periodof one year and the system has not beenrequired to conduct any additionalmonitoring. Systems that qualify forreduced monitoring must continue toconduct daily monitoring at theentrance to the distribution system. Ifthe chlorite concentration at theentrance to the distribution systemexceeds 1.0 mg/L, the system mustresume routine monthly monitoring.

Compliance Determination: A PWS isout of compliance with the chloriteMCL when the arithmetic averageconcentration of any three sample settaken in the distribution system isgreater than 1.0 mg/L.

Bromate. Routine Monitoring: CWSsand NTNCWSs using ozone fordisinfection or oxidation are required totake at least one sample per month foreach treatment plant in the system usingozone. The sample must be taken at theentrance to the distribution systemwhen the ozonation system is operatingunder normal conditions.

Reduced Monitoring: Systems mayreduce monitoring from monthly toonce per quarter if the systemdemonstrates that the annual averageraw water bromide concentration is lessthan 0.05 mg/L, based upon monthlymeasurements for one year.

Compliance Determination: A PWS isin compliance if the running annualarithmetic average of samples,computed quarterly, is less than orequal to the MCL.

Chlorine. Routine Monitoring: As aminimum, CWSs and NTNCWSs mustmeasure the residual disinfectant level(as either free chlorine or total chlorine)at the same points in the distributionsystem and at the same time as totalcoliforms, as specified in § 141.21.Subpart H systems may use the resultsof residual disinfectant concentration

sampling done under the SWTR(§ 141.74(b)(6)(i) for unfiltered systems,§ 141.74(c)(3)(i) for systems that filter)in lieu of taking separate samples.

Reduced Monitoring: Monitoring forchlorine may not be reduced.

Compliance Determination: A PWS isin compliance with the MRDL when therunning annual arithmetic average ofmonthly averages of all samples,computed quarterly, is less than orequal to the MRDL. Notwithstanding theMRDL, operators may increase residualchlorine levels in the distributionsystem to a level and for a timenecessary to protect public health toaddress specific microbiologicalcontamination problems (e.g., includingdistribution line breaks, storm runoffevents, source water contamination, orcross-connections).

Chloramines. Routine Monitoring: Asa minimum, CWSs and NTNCWSs mustmeasure the residual disinfectant level(as either total chlorine or combinedchlorine) at the same points in thedistribution system and at the same timeas total coliforms, as specified in§ 141.21. Subpart H systems may use theresults of residual disinfectantconcentration sampling done under theSWTR (§ 141.74(b)(6) for unfilteredsystems, § 141.74(c)(3) for systems thatfilter) in lieu of taking separate samples.

Reduced Monitoring: Monitoring forchloramines may not be reduced.

Compliance Determination: A PWS isin compliance with the MRDL when therunning annual arithmetic average ofmonthly averages of all samples,computed quarterly, is less than orequal to the MRDL. Notwithstanding theMRDL, operators may increase residualchloramine levels in the distributionsystem to a level and for a timenecessary to protect public health toaddress specific microbiologicalcontamination problems (e.g., includingdistribution line breaks, storm runoffevents, source water contamination, orcross-connections).

Chlorine Dioxide Routine Monitoring:CWSs, NTNCWSs, and TNCWSs mustmonitor for chlorine dioxide only ifchlorine dioxide is used by the systemfor disinfection or oxidation. Ifmonitoring is required, systems musttake daily samples at the entrance to the


distribution system. If the MRDL (0.8mg/L) is exceeded, the system mustconduct additional monitoring.

Additional Monitoring: If any dailysample taken at the entrance to thedistribution system exceeds the MRDL,the system is required to take threeadditional samples in the distributionsystem on the next day. Samples mustbe taken at the following locations.

Systems using chlorine as a residualdisinfectant and operating boosterchlorination stations after the firstcustomer—These systems must takethree samples in the distributionsystem: one as close as possible to thefirst customer, one in a locationrepresentative of average residence time,and one as close as possible to the endof the distribution system (reflectingmaximum residence time in thedistribution system).

Systems using chlorine dioxide orchloramines as a residual disinfectant orchlorine as a residual disinfectant andnot operating booster chlorinationstations after the first customer—Thesesystems must take three samples in thedistribution system as close as possibleto the first customer at intervals of notless than six hours.

Reduced Monitoring: Monitoring forchlorine dioxide may not be reduced.

Compliance Determination: Acuteviolations—If any daily sample taken atthe entrance to the distribution systemexceeds the MRDL and if, on thefollowing day, one or more of the threesamples taken in the distribution systemexceeds the MRDL, the system will bein acute violation of the MRDL andmust issue the required acute publicnotification. Failure to monitor in thedistribution system on the day followingan exceedance of the chlorine dioxideMRDL shall also be considered an acuteMRDL violation.

Nonacute violations—If any twoconsecutive daily samples taken at theentrance to the distribution systemexceed the MRDL, but none of thesamples taken in the distribution systemexceed the MRDL, the system will be innonacute violation of the MRDL. Failureto monitor at the entrance to thedistribution system on the day followingan exceedance of the chlorine dioxideMRDL shall also be considered anonacute MRDL violation.

Important Note: Unlike chlorine andchloramines, the MRDL for chlorinedioxide may not be exceeded for shortperiods of time to address specificmicrobiological contaminationproblems.

TOC. Routine Monitoring: CWSs andNTNCWSs which use conventionalfiltration treatment must monitor eachtreatment plant water source for TOC on

a monthly basis, with samples taken inboth the source water prior to anytreatment and in the treated water nolater than the point of combined filtereffluent turbidity monitoring. At thesame time, systems must monitor forsource water alkalinity.

Reduced Monitoring: Subpart Hsystems with an average treated waterTOC of less than 2.0 mg/L for twoconsecutive years, or less than 1.0 mg/L for one year, may reduce monitoringfor both TOC and alkalinity to onepaired sample per plant per quarter.

Compliance Determination:Compliance criteria for TOC aredependent upon a variety of factors andis discussed elsewhere in this rule.

2. Background and AnalysisThe monitoring requirements in

today’s rule are the same as those in the1994 proposed rule, with the exceptionof requirements for bromide monitoringand chlorite.

Bromide Monitoring for ReducedBromate Monitoring. The 1994 proposalincluded a provision for reducedbromate monitoring for utilities withsource water bromide concentrationsless than 0.05 mg/L. EPA believes thereis a very small likelihood that systemsusing ozone will exceed the bromateMCL if source water bromideconcentrations are below this level. Theprovision did not specify a bromidemonitoring frequency, however. Today’srule allows utilities to reduce bromatemonitoring from monthly to once perquarter if the system demonstrates,based on representative monthlysamples over the course of a year, thatthe average raw water bromideconcentration is less than 0.05 mg/L.

Chlorite Monitoring. The proposedrule required treatment plants usingchlorine dioxide to monitor for chloriteion by taking a three sample set in thedistribution system, once per month,and to analyze these samples using ionchromatography. However, the proposalstates that after the NegotiatingCommittee had agreed to the abovemonitoring scheme for chlorite at its lastmeeting in June, 1993, EPA’s ReferenceDose Committee met and determined adifferent toxicological endpoint forchlorite, based on the identification ofneurobehavioral effects. In light of thisfinding, EPA asserted that it did notbelieve the proposed monthlymonitoring requirement for chlorite wassufficiently protective of public health.Following the proposed rule, EPAacquired additional information onchlorite toxicity, including the results ofa two-generation study sponsored by theCMA. This additional information,discussed elsewhere in this document

(III.A.7), supported EPA’s finding ofneurobehavioral health effects resultingfrom chlorite, along with the rationalefor daily monitoring at the entrance tothe distribution system as a trigger forfurther compliance monitoring in thedistribution system.

3. Summary of CommentsTOC. Many commenters expressed

confusion regarding the raw andfinished water TOC monitoring schemeand their relationship to compliancecalculations. Commenters noted,correctly, that changes in alkalinity andTOC level can move the utility to adifferent box of the TOC removalmatrix, and questioned whether thiswould affect requisite monitoring. As inthe proposal, moving to a different boxof the matrix will not affect monitoringrequirements. Utilities are required totake a minimum of one paired (raw andfinished water) TOC sample per month.Commenters were also concerned thatthe TOC monitoring provisions wouldlimit their ability to take additional TOCsamples for operational control. Thisconcern is unfounded; EPArecommends in the EnhancedCoagulation and Enhanced PrecipitativeSoftening Guidance Manual thatutilities take as many TOC samples asnecessary to maintain properoperational control. EPA alsorecommends that TOC compliancesamples, as opposed to operationalsamples, be taken on a constantschedule or be identified one monthprior to the samples being taken. Thiswill allow utilities to take numerousoperational samples and still provide forunbiased compliance sampling. Systemsmay use their sampling plans for thispurpose.

Chlorite. In the proposal, EPAsolicited comment on changing thefrequency and location of chloritemonitoring in consideration of potentialacute health effects. Commenters statedthat daily monitoring of chlorite wouldbe feasible if amperometric titrationwere allowed as an analytical method.Commenters recommended that dailyamperometric analyses for chlorite beconducted on samples taken from theentrance to the distribution system, andthat weekly or monthly analyses usingion chromatography still be required asa check since ion chromatography is amore accurate analytical method.Several comments stated that dailymonitoring for chlorite would improveoperational control of plants anddecrease the probability of a PWSexceeding the chlorite MCL in thedistribution system. However,commenters requested that if dailymonitoring for chlorite were to be


required, a provision for reducedchlorite monitoring be included as well.

In response to these comments,today’s rule requires treatment plantsusing chlorine dioxide to conduct dailymonitoring for chlorite by taking onesample at the entrance to thedistribution system. This sample may bemeasured using amperometric titration(Standard Method 4500-ClO 2 E).Treatment plants are also required totake a three sample set from thedistribution system once per month, aswas proposed in 1994. In addition,today’s rule requires that on any daythat the concentration of chloritemeasured at the distribution systementrance exceeds the MCL, thetreatment plant must take a threesample set in the distribution system onthe following day. All samples taken inthe distribution system must beanalyzed by ion chromatography(Method 300.0 or 300.1).

EPA recommends that treatmentplants keep chlorite levels below 1.0mg/L and believes that if treatmentplants exceed the MCL in finishedwater, immediate distribution systemtesting is warranted to ensure thatchlorite levels are below 1.0 mg/L. EPAhas not, however, changed thecompliance determination for chloritefrom the 1994 proposed rule.Compliance is still based on the averageof three sample sets taken in thedistribution system. The results of dailymonitoring do not serve as a complianceviolation; rather, they can only triggerimmediate distribution systemmonitoring. Moreover, if the treatmentplant is required to take distributionsystem samples by the results of dailymonitoring and the average chloriteconcentration in the three distributionsystem samples is below the MCL, thenthat sampling will meet the treatmentplant’s requirement for routine monthlymonitoring in the distribution systemfor that month. Today’s rule alsoincludes a provision for reducedchlorite monitoring. Treatment plantsmay reduce routine distribution systemmonitoring for chlorite from monthly toquarterly if the chlorite concentration inall samples both at the entrance to thedistribution system and within thedistribution system are below 1.0 mg/Lfor a period of one year.

In summary, after review of all publiccomments and associated data, EPAbelieves that these provisions forchlorite monitoring will be both feasiblefor treatment plants and provide a levelof protection to public healthcommensurate with the toxic effectsassociated with chlorite.

I. Compliance Schedules

1. Today’s RuleToday’s action establishes revised

compliance deadlines for States to adoptand for public water systems toimplement the requirements in thisrulemaking. Central to thedetermination of these deadlines are theprinciples of simultaneous compliancebetween the Stage 1 DBPR and thecorresponding rules (Interim EnhancedSurface Water Treatment Rule, LongTerm Enhanced Surface WaterTreatment Rule, and Ground WaterRule) to ensure continued microbialprotection, and minimization of risk-risk tradeoffs. These deadlines alsoreflect new legislative provisionsenacted as part of 1996 SDWAamendments. Section 1412 (b)(10) of theSDWA as amended provides PWSs mustcomply with new regulatoryrequirements 36 months afterpromulgation (unless EPA or a Statedetermines that an earlier time ispracticable or that additional time up totwo years is necessary for capitalimprovements). In addition, Section1413(a)(1) provides that States have 24instead of the previous 18 months frompromulgation to adopt new drinkingwater standards.

Applying the 1996 SDWAAmendments to today’s action, thisrulemaking provides that States havetwo years from promulgation to adoptand implement the requirements of thisregulation. Simultaneous compliancewill be achieved as follows.

Subpart H water systems covered bytoday’s rule that serve a population of10,000 or more generally have threeyears from promulgation to comply withall requirements of this rule. In caseswhere capital improvements are neededto comply with the rule, States maygrant such systems up to an additionaltwo years to comply. These deadlineswere consistent with those for theIESWTR.

Subpart H systems that serve apopulation of less than 10,000 and allground water systems will be requiredto comply with applicable Stage 1 DBPRrequirements within five years frompromulgation. Since the Long TermEnhanced Surface Water Treatment Rule(LT1) requirements that apply tosystems under 10,000 and the GroundWater Rule are scheduled to bepromulgated two years after today’s ruleor in November 2000, the net result ofthis staggered deadline is that thesesystems will be required to comply withboth Stage 1 DBPR and LT1/GWRrequirements three years afterpromulgation of LT1/GWR at the sameend date of November 2003. For reasons

discussed in more detail below, EPAbelieves this is both consistent with therequirements of section 1412(b)(10) aswell as with legislative history affirmingthe Reg. Neg. objectives of simultaneouscompliance and minimization of risk-risk tradeoff.

2. Background and AnalysisThe background, factors, and

competing concerns that EPAconsidered in developing thecompliance deadlines in today’s rule areexplained in detail in both the Agency’sIESWTR and Stage 1 DBPR November1997 NODAs. As explained in thoseNODAs, EPA identified four options toimplement the requirements of the 1996SDWA Amendments. The requirementsoutlined above reflect the fourth optionthat EPA requested comment upon inNovember 1997.

By way of background, the SDWA1996 Amendments affirmed several keyprinciples underlying the M–DBPcompliance strategy developed by EPAand stakeholders as part of the 1992regulatory negotiation process. First,under Section 1412(b)(5)(A), Congressrecognized the critical importance ofaddressing risk/risk tradeoffs inestablishing drinking water standardsand gave EPA the authority to take suchrisks into consideration in setting MCLor treatment technique requirements.The technical concerns and policyobjectives underlying M/DBP risk/risktradeoffs are referred to in the initialsections of today’s rule and haveremained a key consideration in EPA’sdevelopment of appropriate compliancerequirements. Second, Congressexplicitly adopted the phased M–DBPregulatory development scheduledeveloped by the NegotiatingCommittee. Section 1412(b)(2)(C)requires that the M/DBP standardsetting intervals laid out in EPA’sproposed ICR rule be maintained evenif promulgation of one of the M–DBPRsis delayed. As explained in the 1997NODA, this phased or staggeredregulatory schedule was specificallydesigned as a tool to minimize risk/risktradeoff. A central component of thisapproach was the concept of‘‘simultaneous compliance’’, whichprovides that a PWS must comply withnew microbial and DBP requirements atthe same time to assure that in meetinga set of new requirements in one area,a facility does not inadvertently increasethe risk (i.e., the risk ‘‘tradeoff’’) in theother area.

A complicating factor that EPA tookinto account in developing today’sdeadlines is that the SDWA 1996Amendments changed two statutoryprovisions that elements of the 1992


Negotiated Rulemaking Agreement werebased upon. The 1994 Stage 1 DBPR andICR proposals provided that 18 monthsafter promulgation large PWS wouldcomply with the rules and States wouldadopt and implement the newrequirements. As noted above, Section1412(b)(10) of the SDWA as amendednow provides that drinking water rulesshall become effective 36 months afterpromulgation (unless the Administratordetermines that an earlier time ispracticable or that additional time forcapital improvements is necessary—upto two years). In addition, Section1413(a)(1) now provides that States have24 instead of the previous 18 months toadopt new drinking water standards thathave been promulgated by EPA.

Today’s compliance deadlinerequirements reflect the principle ofsimultaneous compliance and theconcern with risk/risk tradeoffs. SubpartH systems serving a population of atleast 10,000 will be required to complywith the key provisions of this rule onthe same schedule as they will berequired to comply with the parallelrequirements of the accompanyingIESWTR that is also included in today’sFederal Register.

With regard to subpart H systemsserving fewer than 10,000, EPA believesthat providing a five year complianceperiod under Stage 1 DBPR isappropriate and warranted undersection 1412(b)(10), which expresslyallows five years where necessary forcapital improvements. As discussed inmore detail in the 1997 IESWTR NODA,capital improvements require, ofnecessity, preliminary planning andevaluation. An essential prerequisite ofsuch planning is a clear understandingof final compliance requirements thatmust be met. In the case of the staggeredM/DBP regulatory schedule establishedas part of the 1996 SDWA Amendments,LT1 microbial requirements for systemsunder 10,000 are required to bepromulgated two years after the finalStage 1 DBPR. As a result, small systemswill not even know what their finalcombined compliance obligations areuntil promulgation of the LT 1 rule.Thus, an additional two year periodreflecting the two year Stage 1 DBPR/LT1 regulatory development intervalestablished by Congress is required toallow for the preliminary planning anddesign steps which are inherent in anycapital improvement process.

In the case of ground water systems,the statutory deadline for promulgationof the GWR is May 2002. However, EPAintends to promulgate this rule byNovember 2000, in order to allow threeyears for compliance and still ensuresimultaneous compliance by ground

water systems with the Stage 1 DBPRand the GWR. As in the case of subpartH systems serving fewer than 10,000,system operators will not know untilNovember 2000 what the finalcompliance requirements for both rulesare. EPA thus believes it appropriate togrant the additional two years forcompliance with the Stage 1 DBPRallowed by the statute.

EPA has been very successful inmeeting all of the new statutorydeadlines and is on track for the LT1Rule and GWR. While EPA fully intendsto meet the schedule discussed earlier,if those rules are delayed the Agencywill evaluate all available options toprotect against unacceptable risk-risktrade-offs. Part of this effort is theextensive outreach to systems alreadyunderway to fully inform water suppliesof the likely elements in the upcomingrules. In addition, EPA would considerincluding provisions for streamlinedvariance and/or exemption processingin these rules if they were delayed, inorder to enhance State flexibility inensuring that compliance with the Stage1 DBPR is not required before thecorresponding microbial protection rule.

Under today’s Stage 1 DBPR, EPA hasalready provided small subpart Hsystems and ground water systems thetwo-year extension for capitalimprovements since these systems willnot know with certainty until November2000 if capital improvements will beneeded for simultaneous compliancewith the Stage 1 DBPR and LT1/GWR.States considering whether to grant atwo-year capital improvement extensionfor compliance with the GWR or LT1will also need to consider the impact ofsuch extensions on compliance withtoday’s rule, given that a similarextension for capital improvement hasalready been provided in the initialcompliance schedule for the Stage 1DBPR. EPA believes, however, thatthese systems will generally not requireextensive capital improvements thattake longer than three years to install tomeet Stage 1 DBPR, GWR, and LT1requirements, or will require no capitalimprovements at all. However if needed,EPA will work with States and utilitiesto address systems that require timebeyond November 2003 to comply. Thisstrategy may include exemptions.

In addition, EPA will provideguidance and technical assistance toStates and systems to facilitate timelycompliance with both DBP andmicrobial requirements. EPA willrequest comment on how best to do thiswhen the Agency proposes theLTESWTR and GWR.


Commenters were in generalagreement that the compliance deadlinestrategy contained in the fourth optionof the 1997 NODA did the best job ofcomplying with the requirements to1996 SDWA Amendments and meetingthe objectives of the 1993 Reg. Neg.Agreement that Congress affirmed aspart of the 1996 Amendments.Nonetheless, a number of commentersexpressed concern about the ability oflarge surface water systems that had tomake capital improvements to complywith all requirements of the Stage 1DBPR and IESWTR. They pointed outthat capital improvements include morethan just the construction, but alsofinancing, design, and approval.

EPA believes that the provisions ofSection 1412(b)(10) of the SDWA asamended allow systems the flexibilityneeded to comply. As noted earlier inthis section, States may grant up to anadditional two years compliance timefor an individual system if capitalimprovements are necessary. Moreover,as both of these rules have been undernegotiation since 1992, proposed in1994 and further clarified in 1997, EPAbelieves that most systems have hadsubstantial time to consider how toproceed with implementation and toinitiate preliminary planning. Severalcommenters also supported delaying thepromulgation of the Stage 1 DBPR forground water systems until the GWR ispromulgated, in order to ensuresimultaneous compliance with bothrules. EPA believes that this optionwould not be consistent with the reg-neg agreement, as endorsed by Congress,because the agreement specifies that theStage 1 DBPR will apply to allcommunity and nontransientnoncommunity water systems.Moreover, EPA has committed to theLT1 and GWR promulgation scheduleoutlined above precisely to address thisissue.

In conclusion EPA believes that thecompliance deadlines outlined abovefor systems covered by this rule areappropriate and consistent with therequirements of the 1996 SDWAamendments. The Agency notes,however, that some elements of Option4 outlined in the 1997 NODA apply tosystems that may be covered by futureLong Term Enhanced and Ground Waterrules. EPA intends to follow thedeadline strategy outlined in Option 4for these future rules. However, astoday’s action only relates to the Stage1 DBPR, the Agency will defer finalaction on deadlines associated withfuture rules until those rules,themselves, are finalized.


J. Public Notice Requirements

1. Today’s RuleToday’s action addresses public

notification by promulgating publicnotification language for the regulatedcompounds in 40 CFR Section 141.32(e). EPA takes this opportunity to notethat the 1996 amendments to the SDWArequire the Agency to make certainchanges to the public notice regulations.EPA intends to propose changes to thepublic notice requirements in theFederal Register shortly afterpromulgation of the Stage 1 DBPR.Applicable changes in the public noticerequirements, when they becomeeffective, will supersede today’sprovisions. In general, the publicnotification for the Stage 1 DBPR is notsubstantially changed from thatincluded in the 1994 Proposed Stage 1DBPR (EPA, 1994a).

2. Background and AnalysisUnder Section 1414(c)(1) of the Act,

each owner or operator of a public watersystem must give notice to the personsserved by the system of (1) any violationof any MCL, treatment techniquerequirement, or testing provisionprescribed by an NPDWR; (2) failure tocomply with any monitoringrequirement under section 1445(a) ofthe Act; (3) existence of a variance orexemption; (4) failure to comply withthe requirements of a scheduleprescribed pursuant to a variance orexemption; and (5) notice of theconcentration level of any unregulatedcontaminant for which theAdministrator has required publicnotice.

EPA promulgated the currentregulations for public notification onOctober 28, 1987 (52 FR 41534—EPA,1987). These regulations specify generalnotification requirements, includingfrequency, manner, and content ofnotices, and require the inclusion ofEPA-specified health effects informationin each public notice. The publicnotification requirements divideviolations into two categories (Tier 1and Tier 2) based on the seriousness ofthe violations, with each tier havingdifferent public notificationrequirements. Tier 1 violations includeviolations of an MCL, treatmenttechnique, or a variance or exemptionschedule. Tier 1 violations containhealth effects language specified by EPAwhich concisely and in non-technicalterms conveys to the public the adversehealth effects that may occur as a resultof the violation. States and waterutilities remain free to add additionalinformation to each notice, as deemedappropriate for specific situations. Tier

2 violations include monitoringviolations, failure to comply with ananalytical requirement specified by anNPDWR, and operating under a varianceor exemption.

Today’s final rule contains specifichealth effects language for thecontaminants which are in today’srulemaking. EPA believes that themandatory health effects language is themost appropriate way to inform theaffected public of the potential healthimplications of violating a particularEPA standard.

3. Summary of CommentsEPA received comments on the topic

of the public notification language forTTHM, HAA5, chlorine, chloramines,chlorine dioxide, and enhancedcoagulation. Some commenters notedthat the language in 141.32(e)(79) issatisfactory. One commenter requestedthat the language for DBPs be modifiedto recognize that disinfectants react withnaturally occurring organic andinorganic matter to form DBPs. Somecommenters did not support the use ofthe same public notification languagefor both DBP MCL and enhancedcoagulation treatment techniqueviolations. Several commenterssuggested that the content of the noticesfor chlorine, chloramine, and chlorinedioxide should reflect that disinfectionis an essential step in surface watertreatment. One commenter suggestedthat the language for chlorine dioxideacute effects should be deleted. Othercommenters felt that the notice toconsumers of chlorine dioxideviolations at the treatment facilitywhich do not result in violations in thedistribution system (nonacuteviolations) should not require publicnotification.

In response, EPA has modified thepublic notification language for DBPs toindicate that disinfectants react withnaturally occurring organic andinorganic matter to form DBPs. EPAbelieves it is appropriate to use the samepublic notification language for theenhanced coagulation treatmenttechnique violation as for violations forthe TTHM and HAA5 MCLs, sinceenhanced coagulation is meant to limitexposure to DBPs. EPA believes thecurrent language in the publicnotification language is appropriate toreflect that disinfection is an essentialstep in water treatment. EPA believesthat since the potential health effectsfrom chlorine dioxide are short-termthat it is appropriate to maintain theacute effects language to protect thefetus, infants, and children. In general,the public notification requirements forthe Stage 1 DBPR will not substantially

change from that included in the 1994Proposed Stage 1 DBPR (EPA, 1994a).

K. System Reporting and RecordKeeping Requirements

1. Today’s Rule

The Stage 1 DBPR, consistent with thecurrent system reporting regulationsunder 40 CFR 141.31, requires PWSs toreport monitoring data to States withinten days after the end of the complianceperiod. In addition, systems are requiredto submit the data required in § 141.134.These data are required to be submittedquarterly for any monitoring conductedquarterly or more frequently, and within10 days of the end of the monitoringperiod for less frequent monitoring.Systems that are required to do extramonitoring because of the disinfectantused have additional reportingrequirements specified. This applies tosystems that use chlorine dioxide (mustreport chlorine dioxide and chloriteresults) and ozone (must report bromateresults).

Subpart H systems that useconventional treatment are required toreport either compliance/noncompliance with DBP precursor(TOC) removal requirements or reportwhich of the enhanced coagulation/enhanced softening exemptions they aremeeting. There are additionalrequirements for systems that cannotmeet the required TOC removals andmust apply for an alternate enhancedcoagulant level. These requirements areincluded in § 141.134(b).

Calculation of compliance with theTOC removal requirements is based onnormalizing the percent removals overthe most recent four quarters, sincecompliance is based on that period.Normalization, which would prescribeequal weight to the data collected eachmonth, is necessary since source waterquality changes may change the percentTOC removal requirements from onemonth to another. EPA has developed asample reporting and compliancecalculation sheet that will be availablein the enhanced coagulation guidancemanual to assist utilities in makingthese calculations.


There were no significant commentson the system reporting andrecordkeeping requirements andtherefore EPA is finalizing therequirements as proposed.

L. State Recordkeeping, Primacy, andReporting Requirements

The SDWA provides that States andeligible Indian Tribes may assumeprimary enforcement responsibilities.


Fifty-four out of fifty-six State andterritorial jurisdictions have applied forand received primary enforcementresponsibility (primacy) under the Act.No Tribes have received primacy. Toobtain primacy for the federal drinkingwater regulations, States must adopttheir own regulations which are at leastas stringent as the federal regulations.This section describes the regulationsand other procedures and policies thatStates must adopt to implement thefinal Stage 1 DBPR.

To implement the final rule, States arerequired to adopt the followingregulatory requirements:—Section 141.32, Public Notification;—Section 141.64, MCLs for Disinfection

Byproducts;—Section 141.65, MRDLs for

Disinfectants;—Subpart L, Disinfectant Residuals,

Disinfectant Byproducts, andDisinfection Byproduct Precursors.In addition to adopting regulations no

less stringent than the federalregulations, States must adopt certainrequirements related to this regulationin order to have their program revisionapplications approved by EPA. This rulealso requires States to keep specificrecords and submit specific reports toEPA.

On April 28, 1998, EPA amended itsState primacy regulations at 40 CFR142.12 to incorporate the new processidentified in the 1996 SDWAamendments for granting primaryenforcement authority to States whiletheir applications to modify theirprimacy programs are under review (63FR 23362; EPA, 1998i). The new processgrants interim primary enforcementauthority for a new or revised regulationduring the period in which EPA ismaking a determination with regard toprimacy for that new or revisedregulation. This interim enforcementauthority begins on the date of theprimacy application submission or theeffective date of the new or revised Stateregulation, whichever is later, and endswhen EPA makes a final determination.However, this interim primacy authorityis only available to a State that hasprimacy for every existing nationalprimary drinking water regulation ineffect when the new regulation ispromulgated.

As a result, States that have primacyfor every existing NPDWR already ineffect may obtain interim primacy forthis rule, beginning on the date that theState submits its complete and finalprimacy application for this rule to EPA,or the effective date of its revisedregulations, whichever is later. Inaddition, a State which wishes to obtain

interim primacy for future NPDWRsmust obtain primacy for this rule.

1. State Recordkeeping Requirements

a. Today’s Rule. The currentregulations in § 142.14 require Stateswith primacy to keep various records,including analytical results to determinecompliance with MCLs, MRDLs, andtreatment technique requirements;system inventories; State approvals;enforcement actions; and the issuance ofvariances and exemptions. The Stage 1DBPR requires States to keep additionalrecords of the following, including allsupporting information and anexplanation of the technical basis foreach decision:

(1) Records of determinations madeby the State when the State has allowedsystems additional time to install GACor membrane filtration. These recordsmust include the date by which thesystem is required to have completedinstallation;

(2) Records of systems that arerequired to meet alternative minimumTOC removal requirements or for whomthe State has determined that the sourcewater is not amendable to enhancedcoagulation. These records must includethe results of testing to determinealternative limits and the rationale forestablishing the alternative limits;

(3) Records of subpart H systemsusing conventional treatment meetingany of the enhanced coagulation orenhanced softening exemption criteria;

(4) Register of qualified operators;(5) Records of systems with multiple

wells considered to be one treatmentplant for purposes of determiningmonitoring frequency;

(6) Records of the sampling plans forsubpart H systems serving more than3,300 persons must be keep on file atthe State after submission by the system;

(7) A list of laboratories that havecompleted performance sample analysesand achieved the quantitative results forTOC, TTHMs, HAA5, bromate, andchlorite; and

(8) A list of all systems required tomonitor for disinfectants and DBPsunder subpart L.

b. Background and Analysis. Inaddition to requesting comments on therequirements (1) through (5), and (7)and (8) listed above, EPA also requestedcomments on whether States should berequired to keep the monitoring plansubmitted by systems serving more than3,300 people on file at the State aftersubmission to make it available forpublic review.

c. Summary of Comments. There wereseveral commenters who suggested thatEPA should keep in mind State budgetconstraints when requiring specific

additional recordkeeping requirements.Other commenters stated that theybelieved the requirements werenecessary. EPA understandscommenters concerns with requiringrecordkeeping requirements that areunnecessary, but believes thisinformation is important to conducteffective State program oversight,including the review of State decisionsand their basis. After further review,EPA has decided to eliminate therequirement in the proposal that Statesmust keep records of systems that applyfor alternative TOC performancecriteria. EPA is more concerned with thesystems that are required to meetalternative TOC performance criteria,not the systems that have applied for thealternative performance criteria. Inaddition, EPA has added threerecordkeeping requirements, two ofwhich were originally in the reportingrequirements section and one for whichEPA requested comment.

The first additional requirement willrequire States to keep lists of all systemsrequired to monitor for variousdisinfectants and DBPs (#8 above). Thesecond additional requirement willrequire States to maintain a list oflaboratories that have completedperformance sample analyses andachieved the quantitative results forTOC, TTHMs, HAA5, bromate, andchlorite (#6 above). EPA believes both ofthese recordkeeping requirements arenecessary to ensure adequate EPAprogram oversight. As discussed below,these two requirements are no longer inthe State reporting requirements as EPAhas decided that the requirements in theproposal on State reportingrequirements are not needed on aregular basis, but are needed forprogram oversight. The third additionalrequirement pertains to the request forcomment in the proposal onmaintaining the monitoring planssubmitted by systems (#6 above).Several commenters supported thisadditional requirement stating that itwas a necessary element forimplementing the final rule. Othersbelieved it was not necessary to keepthis on file because the public couldrequest this information from the systemor the State as normal public records.EPA believes that it is important forStates to review, and keep on file thesystems monitoring plan to ensure thatthe PWS is monitoring and calculatingcompliance in accordance with theplan. This will also enable the public toview the plan. Thus, EPA is adding thisrequirement to the final recordkeepingrequirements. In conclusion, based on areview of all public comments the final


rule contains eight State recordkeepingrequirements in addition to thoserequired under current regulations in§ 142.14.

2. Special Primacy Requirementsa. Today’s Rule. To ensure that a State

program includes all the elementsnecessary for an effective andenforceable program under today’s rule,a State application for program revisionapproval must include a description ofhow the State will:

(1) Determine the interim treatmentrequirements for systems grantedadditional time to install GAC andmembrane filtration under 141.64(b)(2).

(2) Qualify operators of communityand nontransient noncommunity watersystems subject to this regulation under141.130(c). Qualification requirementsestablished for operators of systemssubject to 40 CFR Part 141 Subpart H(Filtration and Disinfection) may beused in whole or in part to establishoperator qualification requirements formeeting subpart L requirements if theState determines that the subpart Hrequirements are appropriate andapplicable for meeting subpart Lrequirements.

(3) Approve DPD colorimetric testskits for free and total chlorinemeasurements under 141.131(c)(2).State approval granted under subpart H(§ 141.74(a)(2)) for the use of DPDcolorimetric test kits for free chlorinetesting would be considered acceptableapproval for the use of DPD test kits inmeasuring free chlorine residuals asrequired in subpart L.

(4) Approve parties to conductanalyses of water quality parametersunder 141.132(a)(2) (pH, alkalinity,bromide, and residual disinfectantconcentration measurements). TheState’s process for approving partiesperforming water quality measurementsfor systems subject to subpart Hrequirements may be used for approvingparties measuring water qualityparameters for systems subject tosubpart L requirements, if the Statedetermines the process is appropriateand applicable.

(5) Define criteria to use indetermining if multiple wells are beingdrawn from a single aquifer andtherefore can be considered as a singlesource under 141.132(a)(2). Suchcriteria will be used in determining themonitoring frequency for systems usingonly ground water not under the directinfluence of surface water.

(6) Approve alternative TOC removallevels as allowed under 141.135(b).

b. Background and Analysis. Asdiscussed above, EPA included severalspecial primacy requirements to ensure

that State programs contain all theessential elements for an effectiveprogram. Specifically, EPA believes thespecial requirements are important toensure that the process or approachused by the State for evaluating whetherthe interim treatment in place forsystems granted additional time toinstall GAC or membranes or alternativeenhanced coagulation levels will beprotective of public health. Therequirement to have qualified operatorsis important because the treatmenttechnologies used to comply with theStage 1 DBPR and the IESWTRsimultaneously are complex and willrequire a certain level of expertise. Therequirement to approve parties forconducting analyses of specific waterquality parameters is important becauseeach of the parameters required to betested is critical to a specific componentof the final rule (e.g., bromide ion isimportant because for bromate it ispossible to reduce monitoring frommonthly to once per quarter, if a systemdemonstrates that the average raw waterbromide concentration is less than 0.05mg/L based upon representativemonthly measurements for one year).Finally, it is important to define thecriteria used to determine if multiplewells are to be considered a singlesource as this could have significantimplications for monitoring.

c. Summary of Comments. There wereno significant comments on the primacyrequirements. The only change from theproposal was to delete the requirementthat States must have approved partiesto perform temperature evaluations.This requirement was included in theproposed rule because of the need tohave accurate measurements as a part ofthe process for not allowingpredisinfection credit. Since the finalrule allows credit for compliance withapplicable disinfection requirementsconsistent with the SWTR, thetemperature requirement was removed.

3. State Reporting Requirements

a. Today’s Rule. EPA currentlyrequires in § 142.15 that States report toEPA information such as violations,variance and exemption status, andenforcement actions. The Stage 1 DBPRdoes not add any additional reportingrequirements.

b. Background and Analysis. Thepreamble to the proposed rule includedsix State reporting requirements. Theseincluded:

(1) A list of all systems required tomonitor for various disinfectants anddisinfection byproducts;

(2) A list of all systems for which theState has granted additional time for

installing GAC or membrane technologyand the basis for the additional time;

(3) A list of laboratories that havecompleted performance sample analysesand achieved the quantitative results forTOC, TTHMs, HAA5, bromate, andchlorite;

(4) A list of all systems using multipleground water wells which draw fromthe same aquifer and are considered asingle source for monitoring purposes;

(5) A list of all Subpart H systemsusing conventional treatment which arenot required to operate with enhancedcoagulation, and the reason whyenhanced coagulation is not required foreach system; and

(6) A list of all systems with State-approved alternate performancestandards (alternate enhancedcoagulation levels).

c. Summary of Comments. Severalcommenters stated that the reportingrequirements were not necessary tooperate an oversight program and thatthese reports could be made availablefor EPA review during annual audits.EPA agrees with commenters that thereports are not necessary to operate anoversight program, and that if neededEPA could request this information fromthe States. However, EPA does believeit is important that States maintain thisinformation in their records. Inconclusion, based on commentersconcerns and for the reasons citedabove, the final rule contains noadditional State reporting requirementsother than those required by 142.15.

M. Variances and Exemptions

1. Today’s Rule

Variances may be granted inaccordance with section 1415(a)(1)(A) ofthe SDWA and in accordance with1415(e) and EPA’s regulations.Exemptions may be granted inaccordance with section 1416(a) of theSDWA and EPA’s regulations.

2. Background and Analysis

Variances. The SDWA provides fortwo types of variances—generalvariances and small system variances.Under section 1415(a)(1)(A) of theSDWA, a State which has primaryenforcement responsibility (primacy), orEPA as the primacy agency, may grantvariances from MCLs to those publicwater systems of any size that cannotcomply with the MCLs because ofcharacteristics of the water sources. Theprimacy agency may grant generalvariances to a system on condition thatthe system install the best availabletechnology, treatment techniques, orother means, and provided thatalternative sources of water are not


reasonably available to the system. Atthe time this type of variance is granted,the State must prescribe a complianceschedule and may require the system toimplement additional control measures.Furthermore, before EPA or the Statemay grant a general variance, it mustfind that the variance will not result inan unreasonable risk to health (URTH)to the public served by the public watersystem.

Under section 1413(a)(4), States thatchoose to issue general variances mustdo so under conditions, and in amanner, that are no less stringent thansection 1415. Of course, a State mayadopt standards that are more stringentthan the EPA standards. EPA specifiesBATs for general variance purposes.EPA may identify as BAT differenttreatments under section 1415 forvariances other than the BAT undersection 1412 for MCLs. EPA’s section1415 BAT findings may vary dependingon a number of factors, including thenumber of persons served by the publicwater system, physical conditionsrelated to engineering feasibility, andthe costs of compliance with MCLs. Inthis final rule, EPA is not specifyingdifferent BAT for variances undersection 1415(a). Section 1415(e)authorizes the primacy Agency (EPA orthe State) to issue variances to smallpublic water systems (those serving lessthan 10,000 persons) where the systemcannot afford to comply with an MCLand where the primacy agencydetermines that the terms of thevariances ensure adequate protection ofpublic health (63 FR 1943–57; EPA,1998j). These variances also may onlybe granted where EPA has identified avariance technology under Section1412(b)(15) for the contaminant, systemsize and source water quality inquestion.

Prior to the 1996 SDWA amendments,EPA was required to set the MCL for acontaminant as close to the MCLG as isfeasible. Section 1412(b)(4)(D) of theSDWA states that ‘‘the term ‘‘feasible’’means with the use of the besttechnology, treatment techniques andother means which the Administratorfinds, after examination for efficacyunder field conditions and not solelyunder laboratory conditions, areavailable (taking cost intoconsideration).’’

The cost assessment for the feasibilitydeterminations have historically beenbased upon impacts to regional andlarge metropolitan water systemsserving populations greater than 50,000people. Since large systems served asthe basis for the feasibilitydeterminations, the technical and/orcost considerations associated with

these technologies often were notapplicable to small water systems.While EPA will continue to usefeasibility for large systems in settingNPDWRs, the 1996 amendments to theSDWA specifically require EPA to makesmall system technology assessments forboth existing and future regulations.

The 1996 amendments to the SDWAidentifies three categories of smallpublic water systems that need to beaddressed: (1) those serving apopulation between 3301 to 10,000; (2)those serving a population of 501—3300; and (3) those serving a populationof 26—500. The SDWA requires EPA tomake determinations of availablecompliance technologies and, if needed,variance technologies for each sizecategory. A compliance technology is atechnology that is affordable and thatachieves compliance with the MCL and/or treatment technique. Compliancetechnologies can include point-of-entryor point-of-use treatment units. Variancetechnologies are only specified for thosesystem size/source water qualitycombinations for which there are nolisted compliance technologies.

EPA has completed an analysis of theaffordability of DBP controltechnologies for each of the three sizecategories included above. Based on thisanalysis, multiple affordablecompliance technologies were found foreach of the three system sizes (EPA,1998q and EPA, 1998r) and thereforevariance technologies were notidentified for any of the three sizecategories. The analysis was consistentwith the methodology used in thedocument ‘‘National-Level AffordabilityCriteria Under the 1996 Amendments tothe Safe Drinking Water Act’’ (EPA,1998s) and the ‘‘Variance TechnologyFindings for Contaminants RegulatedBefore 1996’’ (EPA, 1998t).

Exemptions. Under section 1416(a),EPA or a State may exempt a publicwater system from any requirementsrelated to an MCL or treatmenttechnique of an NPDWR, if it finds that(1) due to compelling factors (whichmay include economic factors such asqualification of the PWS as serving adisadvantaged community), the PWS isunable to comply with the requirementor implement measure to develop analternative source of water supply; (2)the exemption will not result in anunreasonable risk to health; and; (3) thePWS was in operation on the effectivedate of the NPWDR, or for a system thatwas not in operation by that date, onlyif no reasonable alternative source ofdrinking water is available to the newsystem; and (4) management orrestructuring changes (or both) cannotreasonably result in compliance with

the Act or improve the quality ofdrinking water.

If EPA or the State grants anexemption to a public water system, itmust at the same time prescribe aschedule for compliance (includingincrements of progress or measures todevelop an alternative source of watersupply) and implementation ofappropriate control measures that theState requires the system to meet whilethe exemption is in effect. Under section1416(b)(2)(A), the schedule prescribedshall require compliance asexpeditiously as practicable (to bedetermined by the State), but no laterthan 3 years after the effective date forthe regulations established pursuant tosection 1412(b)(10). For public watersystems which do not serve more thana population of 3,300 and which needfinancial assistance for the necessaryimprovements, EPA or the State mayrenew an exemption for one or moreadditional two-year periods, but not toexceed a total of 6 years, if the systemestablishes that it is taking allpracticable steps to meet therequirements above.

A public water system shall not begranted an exemption unless it canestablish that either: (1) the systemcannot meet the standard withoutcapital improvements that cannot becompleted prior to the date establishedpursuant to section 1412(b)(10); (2) inthe case of a system that needs financialassistance for the necessaryimplementation, the system has enteredinto an agreement to obtain financialassistance pursuant to section 1452 orany other Federal or state program; or(3) the system has entered into anenforceable agreement to become part ofa regional public water system.

3. Summary of Comments on Varianceand Exemptions

In the 1994 proposal, EPA requestedcomment on whether exemptions to therule should be granted if a system coulddemonstrate to the State that due tounique water quality characteristics itcould not avoid, through the use ofBAT, the possibility of increasing totalhealth risk to its consumers bycomplying with the Stage 1 regulations.The Agency requested informationunder which such a scenario mayunfold. Several commenters supportedgranting exemptions provided a systemcould demonstrate that installation ofBAT will increase the total health risk.

After additional consideration, EPAbelieves it is not appropriate, for severalreasons, to grant exemptions based on ademonstration that the use of BATcould increase the total health risk bycomplying with the Stage 1 DBPR. First,


EPA does not believe the analyticaltools and methodologies are currentlyavailable that would allow adetermination of whether the totalhealth risk from the installation of BATwould increase. Second, at the time ofproposal there was concern that inwaters with high bromideconcentrations it may be possible toincrease the concentrations of certainbrominated DBPs when using precursorremoval processes even though theconcentrations of the TTHMs and HAA5may decrease. Also, at the time ofproposal, the health risks associatedwith many of the brominated DBPs wasunknown, and it was unclear whetherthe benefits of lowering theconcentrations of chlorinated DBPsoutweigh the possible downside risks ofincreasing certain brominated DBPs.Since the proposal, some additionalhealth effects research has beencompleted evaluating the toxicity ofbrominated DBPs. However, thisresearch is still preliminary and noconclusions can be drawn on thepotential for increased risks from thebrominated DBPs. In addition, it isunclear to what extent the use ofprecursor removal processes will changethe concentrations of certain brominatedDBPs. The ICR data should providesome additional information that maybe helpful in this area along withadditional ongoing research. Thisinformation will be available forconsideration in the Stage 2 ruledeliberations. Based on the reasonsstated above, EPA does not believe it isappropriate to allow exemptions to therule based on a finding that theinstallation of BAT would increase thetotal risk from DBPs.

N. Laboratory Certification andApproval

1. Today’s RuleEPA recognizes that the effectiveness

of today’s regulations depends on theability of laboratories to reliably analyzethe regulated disinfectants and DBPs atthe MRDL or MCL, respectively.Laboratories must also be able tomeasure the trihalomethanes andhaloacetic acids at the reducedmonitoring trigger levels, which arebetween 25 and 50 percent of the MCLsfor these compound classes. EPA hasestablished State primacy requirementsfor a drinking water laboratorycertification program for the analysis ofDBPs. States must adopt a laboratorycertification program as part of primacy.[40 CFR 142.10(b)]. EPA has alsospecified laboratory requirements foranalyses of DBP precursors anddisinfectant residuals which must be

conducted by approved parties. [40 CFR141.89 and 141.74]. EPA’s ‘‘Manual forthe Certification of LaboratoriesAnalyzing Drinking Water’’, EPA 815–B–97–001—(EPA, 1997g), specifies thecriteria for implementation of thedrinking water laboratory certificationprogram.

In today’s rule, EPA is promulgatingMCLs for TTHMs, HAA5, bromate, andchlorite. Today’s rule requires that onlycertified laboratories be allowed toanalyze samples for compliance withthe proposed MCLs. For thedisinfectants and certain otherparameters in today’s rule, which haveMRDLs or monitoring requirements,EPA is requiring that analyses beconducted by a party acceptable to theState.

Performance evaluation (PE) samples,which are an important tool in theSDWA laboratory certification program(laboratories seeking certification) maybe obtained from a PE providerapproved by the National Institute ofScience and Technology (NIST). Toreceive and maintain certification, alaboratory must use a promulgatedmethod and, at least once per year,successfully analyze an appropriate PEsample. In the drinking water PEstudies, NIST-approved providers willprovide samples for bromate, chlorite,five haloacetic acids, fourtrihalomethanes, free chlorine, andalkalinity. The NIST-approved PEproviders will provide total chlorineand TOC samples in the wastewater PEstudies and have the potential toprovide these samples for drinkingwater studies. Due to the lability ofchlorine dioxide, EPA does not expecta suitable PE sample can be designed forchlorine dioxide measurements.

PE Sample Acceptance Limits forLaboratory Certification. Historically,EPA has set minimum PE acceptancelimits based on one of two criteria:statistically derived estimates or fixedacceptance limits. Statistical estimatesare based on laboratory performance inthe PE study. Fixed acceptance limitsare ranges around the true concentrationof the analyte in the PE sample. Today’srule combines the advantages of theseapproaches by specifying statistically-derived acceptance limits around thestudy mean, within specified minimumand maximum fixed criteria.

EPA believes that specifyingstatistically-derived PE acceptancelimits with upper and lower bounds onacceptable performance provides theflexibility necessary to reflectimprovement in laboratory performanceand analytical technologies. Theacceptance criteria maintain minimumdata quality standards (the upper

bound) without artificially imposingunnecessarily strict criteria (the lowerbound). Therefore, EPA is establishingthe following acceptance limits formeasurement of bromate, chlorite, eachhaloacetic acid, and eachtrihalomethane in a PE sample.

EPA is defining acceptableperformance for each chemicalmeasured in a PE sample from estimatesderived at a 95% confidence intervalfrom the data generated by a statisticallysignificant number of laboratoriesparticipating in the PE study. However,EPA requires that these acceptancecriteria not exceed ±50% nor be lessthan ±15% of the study mean. Ifinsufficient PE study data are availableto derive the estimates required for anyof these compounds, the acceptancelimit for that compound will be set at±50% of the study true value. The truevalue is the concentration of thechemical that EPA has determined wasin the PE sample.

EPA recognizes that when usingmultianalyte methods, the datagenerated by laboratories that areperforming well will occasionallyexceed the acceptance limits. Therefore,to be certified to perform compliancemonitoring using a multianalytemethod, laboratories are required togenerate acceptable data for at least 80%of the regulated chemicals in the PEsample that are analyzed with themethod. If fewer than five compoundsare included in the PE sample, data foreach of the analytes in that sample mustmeet the minimum acceptance criteriain order for the laboratory to becertified.

Approval Criteria for Disinfectantsand Other Parameters. Today’s ruleestablishes MRDLs for the threedisinfectants—chlorine, chloramines,and chlorine dioxide. In addition, EPAhas established monitoringrequirements for TOC, alkalinity, andbromide; there are no MCLs for theseparameters. In previous rules [40 CFR141.28, .74, and .89], EPA has requiredthat measurements of alkalinity,disinfectant residuals, pH, temperature,and turbidity be made with an approvedmethod and conducted by a partyapproved (not certified) by the State. Intoday’s rule, EPA requires that samplescollected for compliance with today’srequirements for alkalinity, bromide,residual disinfectant, and TOC beconducted with approved methods andby a party approved by the State.

Other Laboratory PerformanceCriteria. For all contaminants andparameters required to be monitored intoday’s rule, the States may imposeother requirements for a laboratory to be


certified or a party to be approved toconduct compliance analyses.

2. Background and AnalysisThe laboratory certification and

approval requirements that today’s ruleestablishes are unchanged from thoseproposed by EPA in 1994.

3. Summary of CommentsEPA received few comments on

laboratory certification and approval.Commenters requested clarification ofthe use of the ±50% upper bound and±15% lower bound, along with the useof statistically derived limits. EPAbelieves that statistically derived limitsprovide flexibility to allow laboratorycertification standards to reflectimprovement in laboratory performanceand analytical technologies. Aslaboratories become more proficient inconducting these analyses, statisticallyderived acceptance limits may drop.However, to prevent the exclusion oflaboratories capable of producing dataof sufficient quality for compliancepurposes, EPA has established a lowerbound for acceptance limits of ±15%.EPA is imposing an upper bound onacceptable performance to establishminimum data quality standards.Results outside of this range haveunacceptable accuracy for compliancedeterminations. These upper and lowerbounds were not determinedstatistically; they are the data qualityobjectives the Agency has determined asacceptable.

IV. Economic AnalysisUnder Executive Order 12866,

Regulatory Planning and Review, EPAmust estimate the costs and benefits ofthe Stage 1 DBPR in a Regulatory ImpactAnalysis (RIA) and submit the analysisto Office of Management and Budget(OMB) in conjunction with publishingthe final rule. EPA has prepared an RIAto comply with the requirements of thisOrder. This section provides a summaryof the information from the RIA for theStage 1 DBPR (USEPA 1998g).

A. Today’s RuleEPA has estimated that the total

annualized cost, for implementing theStage 1 DBPR is $701 million in 1998dollars (assuming a 7 percent cost ofcapital). This estimate includesannualized treatment costs to utilities($593 million), start-up and annualizedmonitoring costs to utilities ($91.7million), and startup and annualizedmonitoring costs to states ($17.3million). Annualized treatment costs toutilities includes annual operation andmaintenance costs ($362 million) andannualized capital costs assuming 7

percent cost of capital ($230 million).The basis for these estimates, andalternate cost estimates using differentcost of capital assumptions aredescribed later in this section. While thebenefits of this rule are difficult toquantify because of the uncertaintyassociated with risks from exposure toDBPs (and the resultant reductions inrisk due to the decreased exposure fromDBPs), EPA believes that there is areasonable likelihood that the benefitswill exceed the costs. Variousapproaches for assessing the benefits areconsidered and described in the benefitsand net benefits sections of thispreamble.

B. Background

1. Overview of RIA for the ProposedRule

In the RIA for the 1994 proposedStage 1 DBPR (EPA, 1994i) EPAestimated the national capital andannualized utility costs (sum ofamortized capital and annual operatingcosts, assuming 10% cost of capital) forall systems at $4.4 billion and $1.04billion, respectively. The cost andreduction in DBP exposure estimates ofthe 1994 RIA were derived using aDisinfection Byproduct RegulatoryAnalysis Model (DBPRAM). TheDBPRAM consisted of a collection ofanalytical models which used MonteCarlo simulation techniques to producenational forecasts of compliance andexposure reductions for differentregulatory scenarios. The TWG,representing members of the Reg. Neg.Committee, used the best availableinformation at the time as inputs to theDBPRAM, and for making furtheradjustments to the model predictions.The Stage 1 DBPR compliance andexposure forecasts were affected byconstraints imposed by the 1994proposed IESWTR option which wouldhave required systems to provideenough disinfection, while not allowingfor disinfection credit prior to TOCremoval by enhanced coagulation, toachieve a 10¥4 annual risk of infectionfrom Giardia (EPA, 1994a). Thecompliance forecast assumed that asubstantial number of systems wouldneed to install advanced technologies tomeet the Stage 1 DBPR because ofneeding to achieve the 10¥4 annual risklevel from Giardia while no longer beingallowed disinfection credit prior to TOCremoval.

Predicted benefits for the proposedStage 1 DBPR were derived assuming abaseline risk ranging from 1 to 10,000cancer cases per year (based on analysisof available toxicological andepidemiological data) and assuming

reductions in the cancer risks wereproportional to reductions in TTHM,HAA5, or TOC levels (predicted fromcompliance forecasts). Negotiatorsagreed that the range of possible risksattributed to chlorinated water shouldconsider both toxicological data andepidemiological data, including theMorris et al. (1992) estimates. Noconsensus, however, could be reachedon a single likely risk estimate.Therefore, the predicted benefits for theproposal ranged from one to severalthousands cases of cancer being avoidedper year after implementation of theStage 1 DBPR. Despite, the uncertaintyin quantifying the benefits from theStage 1 DBPR, the Reg. Neg. Committeerecognized that risks from chlorinatedwater could be large, and thereforeshould be reduced. The Reg. Neg.Committee also recommended that theproposed Stage 1 DBPR provided thebest means for reducing risks from DBPsuntil better information becomeavailable.

For a more detailed discussion of thecost and benefit analysis of the 1994proposed DBPR refer to the preamble ofthe proposed rule (EPA, 1994a) and theRIA for the proposed rule (EPA, 1994i).

2. Factors Affecting Changes to the 1994RIA

a. Changes in Rule Criteria. Based onthe new data reflecting the feasibility ofenhanced coagulation, as discussedpreviously, the enhanced coagulationrequirements were modified bydecreasing the percent TOC removalrequirements by 5 percent for systemswith low TOC level waters (i.e., 2–4 mg/L TOC). These new percent TOCremoval requirements were used withnew source and finished water TOCoccurrence data to revise the estimatesfor the number of systems requiringenhanced coagulation.

The IESWTR was revised from theproposal to allow inactivation credit fordisinfection prior to and during stagesof treatment for precursor removal.Also, the proposed IESWTR was revisedto include disinfection benchmarkcriteria, in lieu of requiring treatment toan acceptable risk level, to preventincreases in microbial risk whilesystems complied with the Stage 1DBPR. These two rule changes wereconsidered in revising the forecasts ofcompliance and changes in exposureresulting from the Stage 1 DBPR.

b. New Information Affecting DBPOccurrence and Compliance Forecasts.Since the rule was proposed, newsources of data have become availablethat were used to update the 1994 RIA.The new data includes:


• Updated costs for differenttreatment technologies (e.g.,membranes) used in the DBP Cost andTechnology Document, (EPA, 1998k);

• 1996 data from the AWWA WaterIndustry Data Base on TOC, TTHM andHAA5 occurrence, and disinfectionpractices;

• Plant schematics of treatmentprocesses for ICR utilities;

• Research data from numeroussources regarding the efficacy ofenhanced coagulation for precursorremoval and resultant DBP formation(Krasner, 1997; and EPA, 1997b);

• New research results produced injar tests by TWG members documentingthe effect of moving the point ofpredisinfection under varyingconditions (Krasner, 1997 and EPA,1997b).

This new information has beendescribed in the 1997 DBP NODA (EPA,1997b). Public comments received in1997, supported using the aboveinformation in revising the decision treeanalysis. Discussion on the decision treechanges are in section IV.C of thispreamble.

c. New Epidemiology Information.Since the proposal, EPA has completed

an reassessment of the Morris et al.(1992) meta-analysis (Poole, 1997).Review of the meta-analysis indicatedthat the estimate of cancer cases hadlimited utility for risk assessmentpurposes for methodological reasons(EPA, 1998l and EPA, 1998m). EPA hasdecided not to use the Morris et al.(1992) meta-analysis to estimate thepotential benefits from the Stage 1DBPR. EPA has considered newepidemiology studies conducted sincethe time of proposal and completed anassessment of the potential number ofbladder cancer cases that could beattributed to exposure from chlorinatedsurface waters. Based on this assessmentof epidemiological studies, EPAestimates that between 1100–9300bladder cancer cases per year could beattributed to exposure to chlorinatedsurface waters (EPA, 1998c). Due to thewide uncertainty in these estimates, thetrue number of attributable cases couldalso be zero. The basis for these bladdercancer case estimates and potentialreductions in risk resulting from theStage 1 DBPR is discussed further in thebenefits and net benefits sections thatfollow.

C. Cost Analysis

National cost estimates of compliancewith the Stage 1 DBPR were derivedfrom estimates of utility treatment costs,monitoring and reporting costs, andstart-up costs. Utility treatment costswere derived using compliance forecastsof technologies to be used and unit costsfor the different technologies.

1. Revised Compliance Forecast

The TWG, supporting the M–DBPAdvisory Committee, used the 1996AWWA Water Industry Data Base(WIDB) to reevaluate the compliancedecision tree used in the RIA for the1994 proposal. The WIDB providedoccurrence data on TOC level in rawwater and finished water, TTHM andHAA5 levels within distributionsystems, and information onpredisinfection practices.

The above information was used topredict treatment compliance choicesthat plants would likely make under theStage 1 DBPR. Table IV–1 illustrateshow the compliance forecast changedfor large systems using surface watersince the time of proposal.

TABLE IV–1.—COMPARISONS OF COMPLIANCE FORECASTS FOR SURFACE WATER SYSTEMS SERVING ≥10,000POPULATION FROM THE 1994 PROPOSAL AND FINAL RULE

Treatment1994 1998

# systems % systems # systems % systems

(A) No Further Treatment ............................................................................................. 386 27.7 544 39.0(B) Chlorine/Chloramines ............................................................................................. 41 2.9 231 16.6(C) Enhanced Coagulation + Chloramines .................................................................. 136 9.7 265 19.0(D) Enhanced Coagulation + Chlorine ......................................................................... 600 43.0 265 19.0(E) Ozone, Chlorine Dioxide, Granular Activated Carbon, Membranes ...................... 232 16.6 90 6.5

Total * ..................................................................................................................... 1,395 100 1,395 100

* May not add to total due to independent rounding.

Notable is that the percentage of systemspredicted to use advanced technologies(ozone, chlorine dioxide, GAC, ormembrane) dropped from 17 percent to6.5 percent since proposal, and thepercentage of systems not affected bythe rule increased from 28 percent to 39percent. This shift in predictedcompliance choices is mainly attributedto less stringent disinfectionrequirements under the IESWTR whichwould reduce the formation of DBPsand reduce the number of systemsrequiring treatment to meet the Stage 1

DBPR. It also appears that a substantialnumber of systems may have alreadymade treatment changes to comply withthe 1994 proposed rule.

Table IV–2 illustrates how thecompliance forecast changed for smallsystems using surface water since thetime of proposal. As for large systems,the percentage of systems predicted touse advanced technologies droppedsubstantially, from 17 percent to 6.5percent. This drop in use of advancedtechnology (i.e., ozone/chloramines and

membrane technologies) is attributed tothe change in the IESWTR (as describedabove) from the time of proposal.However, unlike for large systems, theoverall percentage of systems predictedto require treatment modifications didnot change. A higher percentage ofsmall systems (70 percent) are predictedto be affected than large systems (61percent) because previously smallersystems did not have to comply with aTTHM standard.


TABLE IV–2.—COMPARISON OF COMPLIANCE DECISION TREE FOR SURFACE WATER SYSTEMS SERVING <10,000POPULATION FROM THE 1994 PROPOSAL AND FINAL RULE

1994 1998


No Further Treatment ................................................................................................... 1,549 30 1,549 30Number of Affected Systems ....................................................................................... 3,615 70 3,615 70Treatment:

Chlorine/Chloramine .............................................................................................. 155 3.0 826 16.0Enhanced Coagulation .......................................................................................... 2,169 42.0 1,983 38.4Enhanced Coagulation/Chloramine ....................................................................... 465 9.0 465 9.0Ozone/Chloramine ................................................................................................. 258 5.0 184 3.6Enhanced Coagulation+Ozone, Chloramine ......................................................... 258 5.0 0 0Membranes ............................................................................................................ 310 6.0 157 3.0

Table IV–3 illustrates the complianceforecast for ground water systems. Thisforecast did not change from the time ofproposal. A smaller percentage of small

ground water systems are anticipated toneed treatment changes (12 percent)than large ground water systems (15percent) because the use of disinfectants

is more prevalent in large versus smallground water systems.

TABLE IV–3.—COMPLIANCE DECISION TREE FOR ALL GROUND WATER SYSTEMS

Systems <10,000 Systems ≥10,000


No Further Treatment ....................................................................................................... 59,847 88 1,122 85Percentage of Affected Systems ...................................................................................... 8,324 12 198 15Treatment:

Chlorine/Chloramine .................................................................................................. 5,403 8 119 9Ozone/Chloramine ..................................................................................................... 0 0 26 2Membranes ................................................................................................................ 2,921 4 53 4

2. System Level Unit CostsTables IV–4 and IV–5 present the unit cost estimates in 1998 dollars that were utilized for each of the different

treatment technologies in each system size category. Unit costs are presented in $ per 1000 gallons which includesoperation and maintenance costs and amortized capital costs (using a 7% discount rate and a 20 year amortizationperiod). One dollar per thousand gallons equates to approximately $100 per household per year as an average forcommunities in the U.S. More detailed information on these unit costs is available from the EPA’s Cost and TechnologyDocument (EPA, 1998k).

TABLE IV–4.—SURFACE WATER SYSTEMS COSTS FOR DBP CONTROL TECHNOLOGIES ($/KGAL) AT 7% COST OF CAPITAL

Population size category

25–100 100–500 500–1K 1–3.3K 3.3–10K 10–25K 25–50K 50–75K 75–100K 100K–500K 500K–1M >1M

Chlorine/Chloramine .............. 0.71 0.19 0.06 0.03 0.03 0.02 0.01 0.01 0.01 0.01 0.01 0.01Enhanced Coagulation (EC) 0.15 0.13 0.12 0.11 0.09 0.08 0.07 0.07 0.07 0,07 0.06 0.06EC/Chloramine ...................... 0.87 0.32 0.18 0.14 0.12 0.09 0.08 0.08 0.08 0.07 0.07 0.07Ozone/Chloramine ................. 12.67 3.21 1.05 0.52 0.38 0.23 0.13 0.10 0.08 0.06 0.04 0.04EC+Ozone, Chloramine ........ 12.82 3.34 1.17 0.63 0.47 0.30 0.20 0.17 0.15 0.13 0.11 0.10EC+GAC10 ............................ 6.24 2.43 1.21 0.81 0.59 0.46 0.37 0.35 0.29 0.24 0.19 0.16EC+GAC20 ............................ 14.11 5.87 3.45 2.45 1.87 1.48 1.05 1.00 0.90 0.64 0.48 0.41Chlorine Dioxide .................... 24.33 5.73 1.65 0.64 0.24 0.11 0.07 0.07 0.06 0.05 0.04 0.04Membranes ............................ 3.40 3.47 3.39 2.65 1.72 0.96 0.96 0.87 0.87 0.87 0.87 0.87

TABLE IV–5.—GROUND WATER SYSTEMS COSTS FOR DBP CONTROL TECHNOLOGIES ($/KGAL) AT 7% COST OF CAPITAL

Population size category

25–100 100–500 500–1K 1–3.3K 3.3–10K 10–25K 25–50K 50–75K 75–100K 100K–500K 500K–1M >1M

Chlorine/Chloramine .............. 0.72 0.19 0.06 0.03 0.03 0.02 0.01 0.01 0.01 0.01 0.01 0.01Ozone/Chloramine ................. 12.67 3.21 1.05 0.52 0.38 0.23 0.13 0.10 0.08 0.06 0.04 0.04Membranes ............................ 3.41 3.47 3.39 2.65 1.72 0.96 0.96 0.87 0.87 0.87 0.87 0.87

3. National CostsTable IV–6 provides a detailed summary of national costs in 1998 dollars under the Stage 1 DBPR for different

cost of capital assumptions under a 20 year amortization period. A cost of capital rate of 7 percent was used tocalculate the unit costs for the national compliance cost model. This rate represents the standard discount rate preferredby OMB for benefit-cost analyses of government programs and regulations. The 3 percent and 10 percent rates areprovided as a sensitivity analysis to show different assumptions about the cost of capital that would affect estimated


costs. The 10 percent rate also provides a link to the 1994 Stage 1 DBPR cost analysis which was based on a 10percent rate. EPA believes that the cost estimates presented in Table IV–6 are probably within +/¥30 percent. Uncertaintyaround the cost estimates pertain to compliance forecast estimates, unit cost estimates for the different technologiesas they may pertain to individual sites, and estimated costs associated with monitoring.

TABLE IV–6.—SUMMARY OF COSTS UNDER THE STAGE 1 DBPR ($000)

Utilities CostsSurface water systems Ground water systems

All systemsSmall Large Total Small Large Total

Summary of Costs at 3 Percent Cost of Capital

Treatment CostsTotal Capital Costs .................................... 242,652 554,564 797,216 997,537 528,539 1,526,076 2,323,292Annual O&M .............................................. 23,068 201,308 224,376 83,910 54,243 137,153 362,530Annualized Capital Costs .......................... 16,326 37,161 53,487 67,287 35,618 102,905 156,392Annual Utility Treatment Costs ................. 39,394 238,469 277,863 151,197 89,861 240,058 518,922Monitoring and Reporting Cost:

Start-Up Costs ................................... 59 28 87 674 26 700 787Annual Monitoring .............................. 10,867 14,619 25,486 38,803 26,326 65,129 90,615

State Costs:Start-Up Costs ................................... .................... .................... .................... .................... .................... .................... 2,919Annual Monitoring .............................. .................... .................... .................... .................... .................... .................... 13,243

Total Annual Costs at 3 PercentCost of Capital ........................ .................... .................... .................... .................... .................... .................... 626,486


Total Capital Costs .................................... 242,652 554,564 797,216 997,537 528,539 1,526,076 2,323,292Annual O&M .............................................. 23,068 201,308 224,376 83,910 54,243 137,153 362,530Annualized Capital Costs .......................... 22,786 62,355 85,141 94,403 50,046 144,499 229,590Annual Utility Treatment Costs ................. 45,855 263,663 309,518 178,313 104,289 282,602 592,120Monitoring and Reporting Cost:

Start-Up Costs ................................... 82 39 121 946 36 982 1,103Annual Monitoring .............................. 10,867 14,619 25,486 38,803 26,326 65,129 90,615




Total Capital costs .................................... 242,652 554,564 797,216 997,537 528,539 1,526,076 2,323,292Annual O&M .............................................. 23,068 201,308 224,376 83,910 54,243 137,153 362,530Annualized Capital Costs .......................... 28,423 74,639 103,062 117,328 62,522 179,850 282,912Annual Utility Treatment Costs ................. 51,491 275,947 327,438 201,238 116,765 317,003 645,442Monitoring and Reporting Cost:

Start-Up Costs ................................... 102 48 150 1,177 45 1,222 1,372Annual Monitoring .............................. 10,867 14,619 25,486 38,803 26,326 65,129 90,615



The total national costs of the finalStage 1 DBPR are less than estimated inthe RIA for the proposed rule in 1994.The estimated capital costs of the 1994proposal in 1998 dollars is $4.97 billionand the total annual cost (assuming a 10percent cost of capital as was assumedin 1994) is $1.3 billion. The drop innational costs from the 1994 proposal ismainly attributed to the lowering of thenumber of surface water systems

anticipated to need advancedtechnologies and lower membranetechnology costs as described above.

D. Benefits Analysis

1. Exposure Assessment

A large portion of the U.S. populationis exposed to DBPs via drinking water.Over 200 million people in the U.S. areserved by PWSs which apply adisinfectant (e.g., chlorine) to water in

order to provide protection againstmicrobial contaminants. Because of thelarge number of people potentiallyexposed to DBPs, there is a substantialconcern for any health risks which maybe associated with exposure to DBPs.

Several factors are necessary to assessthe exposure to DBPs: the size of thepopulation potentially at risk; themethod and rate of ingestion; and theconcentration of DBPs in drinking


water. Because DBPs are formed indrinking water by the reaction ofdisinfectants with natural organic andinorganic matter, the population at riskis identified as the population served bydrinking water systems that disinfect.The population served by each of foursystem categories, taken from recentSafe Drinking Water Act Information

System data (SDWIS) is estimated inTable IV–7. Based on recent informationfrom SDWIS, it was assumed that allsurface water systems disinfect and aportion of ground water systemsdisinfect (95 percent by populationamong large systems and 83 percent bypopulation among small systems).Approximately 239 million persons are

estimated to be served by water systemsthat disinfect and are potentiallyexposed to DBPs. This widespreadexposure represents over 88 percent ofthe total U.S. population (270 million).The route of exposure is throughdrinking disinfected tap water.

TABLE IV–7.—POPULATION POTENTIALLY EXPOSED TO DBPS

Populationserved

% of popu-lation receiv-

ing disinfectedwater

Populationserved by sys-tems that dis-

infect

Large Surface Water: >10,000 persons ....................................................................................... 141,297,000 100 141,297,000Small Surface Water: <10,000 persons ....................................................................................... 17,232,000 100 17,232,000Large Ground Water: >10,000 persons ....................................................................................... 56,074,000 95 53,270,300Small Ground Water: < 10,000 persons ...................................................................................... 32,937,000 83 27,337,710

Total ...................................................................................................................................... ........................ ........................ 239,137,010

In general, little data are available onthe occurrence of DBPs on a nationalbasis. Although there is sufficientoccurrence data available for THMs inlarge water systems to develop anational occurrence distribution for thatsubset of systems, data are limited forsmall water systems. Similarly, someoccurrence data for HAA5 are availablefor large surface water systems, but notsmall surface water and groundwatersystems.

2. Baseline Risk Assessment Based onTTHM Toxicological Data

EPA performed a quantitative riskassessment using the dose-responseinformation on THMs. This assessment,however, captures only a portion of thepotential risk associated with DBPs indrinking water. It is not possible, givenexisting toxicological and exposuredata, to gauge how much of the totalcancer risk associated with theconsumption of chlorinated drinkingwater is posed by TTHMs alone. Anassessment of THMs, however, providessome estimation of the potential humanrisk, albeit limited.

Performing the risk assessment basedon TTHM toxicological data requiresmaking several assumptions andextrapolations (from a nonhumanspecies to humans, from high doses inthe laboratory study to lowerenvironmental exposures, and from anondrinking water route to the relevantroute of human exposure). Assumptionsare also made about the occurrence ofTTHMs and the individual DBPs. EPAestimated the pre-Stage 1 DBPR TTHMconcentration levels by calculating aweighted average (based on populationsreceiving disinfected waters) of TTHMlevels among the different system type

categories described in Table IV–7.TTHM levels among systems servinggreater than 10,000 people wereestimated based on averageconcentrations among systems inAWWA’s WIDB. TTHM levels insystems serving less than 10,000 peoplewere estimated through modeling.Modeling consisted of applying TTHMpredictive equations to estimates of DBPprecursor levels and treatmentconditions. The mean weighted averagebaseline TTHM concentrations amongall the system type categories was 44 µg/L.

Occurrence data from an EPA DBPfield study indicate that chloroform isthe most common THM (in general,about 70 percent of total THMs), withbromoform being the least common (1percent). Bromodichloromethane has anoccurrence of approximately 20 percentof the total THMs, withdibromochloromethane comprising thefinal 8 percent of the total THMs. In theabsence of more detailed occurrencedata, these proportions are used todivide the average TTHM concentrationinto the concentration for the fourindividual compounds.

Two estimates of risk factors wereused to estimate the cancer incidence.The first set of lifetime unit risk factorsrepresent the upper 95 percentconfidence limit of the dose-responsefunction. The second estimate oflifetime unit risk is the maximumlikelihood estimate used in the 1994analysis that represents the centraltendency of the dose-response function(Bull, 1991). The annual unit risk iscalculated by dividing the lifetime riskby a standard assumption of 70 yearsper lifetime. To calculate the annualincidence of cancer due to consumption

of TTHMs in drinking water, the annualdrinking water unit risk is multiplied bythe number of units, in this case theconcentration of TTHMs in µg/L, brokenout into individual THMs based on theproportions presented above. Based onthese cancer risk estimates derived fromlaboratory animal studies, the annual95th percentile upper bound number ofcancer cases attributable to TTHMs isapproximately 100. This means thatthere is a 95 percent chance that theannual number of cases are less than orequal to 100. Using the maximumlikelihood or ‘‘best’’ estimates, theannual number of cancer cases is about2.

3. Baseline Analysis Based onEpidemiology Data

Epidemiological studies can be usedto assess the overall population riskassociated with a particular exposure.Since the late 1970s, epidemiologicalinvestigations have attempted to assesswhether chlorinated drinking watercontributes to the incidence of bladder,colon, rectal, and other cancers. Severalstudies have reported a weakassociation between bladder cancer andexposure to chlorinated drinking water,but a causal relationship has not beenconfirmed (Freedman, et al., 1997).

Several cancer epidemiologicalstudies examining the associationbetween exposure to chlorinated surfacewater and cancer were publishedsubsequent to the 1994 proposed ruleand the 1992 meta-analysis. In general,these new studies are better designedthan the studies published prior to the1994 proposal. The new studies includeincidence of disease, interviews withthe study subjects, and better exposureassessments. More evidence is available


on bladder cancer for a possibleassociation to exposure to chlorinatedsurface water than other cancer sites.Because of the limited data available forother cancer sites such as colon andrectal cancer, the RIA focuses onbladder cancer.

Based on the best studies, a range ofpotential risks was developed throughthe use of the population attributablerisk (PAR) concept. Epidemiologists usePAR to quantify the fraction of diseaseburden in a population (e.g., bladdercancer) that could be eliminated if theexposure (e.g., chlorinated drinkingwater) was absent. PAR (also referred toas attributable risk, attributable portion,or etiologic fraction) provides aperspective on the potential magnitudeof risks associated with variousexposures under the assumption ofcausality. For example, the NationalCancer Institute estimates that there willbe 54,500 new cases of bladder cancerin 1997. If data from an epidemiologicalstudy analyzing the impact ofconsuming chlorinated drinking waterreports a PAR of 1 percent, it can beestimated that 545 (54,500 × .01)bladder cancer cases in 1997 may beattributable to chlorinated drinkingwater.

Under the Executive Order #12866that requires EPA to conduct a RIA, EPAhas chosen to estimate an upper boundbladder cancer risk range for chlorinateddrinking water using the PAR. EPAsuggested this approach in the 1998NODA (EPA, 1998a). While EPArecognizes the limitations of the currentepidemiologic data base for makingthese estimates, the Agency considersthe data base reasonable for use indeveloping an upper bound estimate ofbladder cancer risk for use in the RIA.In light of the toxicological evidence,EPA recognizes that the risks fromchlorinated drinking water may beconsiderably lower than those derivedfrom the currently availableepidemiological studies. EPA selectedstudies for inclusion in the quantitativeanalysis if they contained the pertinentdata to perform a PAR calculation andmet all three of the following criteria:

1. The study was a population-based,case-control, or cohort study conducted

to evaluate the relationship betweenexposure to chlorinated drinking waterand incidence of cancer cases, based onpersonal interviews; (all finally selectedstudies were population-based, case-control studies)

2. The study was of high quality andwell designed (e.g., adequate samplesize, high response rate, adjusted forknown confounding factors); and,

3. The study had adequate exposureassessments (e.g., residential histories,actual THM data).

Using the above criteria, five bladdercancer studies were selected forestimating the range of PARs.

• Cantor, et al., 1985;• McGeehin, et al., 1993;• King and Marrett, 1996;• Freedman, et al., 1997; and• Cantor, et al., 1998.The PARs from the five bladder

cancer studies ranged from 2 percent to17 percent. These values were derivedfrom measured risks (Odds Ratio andRelative Risk) based on the number ofyears exposed to chlorinated surfacewater. Because of the uncertainty inthese estimates, it is possible that thePAR could also be zero. Theuncertainties associated with these PARestimates are large due to the commonprevalence of both the disease (bladdercancer) and exposure (chlorinateddrinking water).

In order to apply these PAR estimatesto the U.S. population to estimate thenumber of bladder cancer casesattributable to DBPs in drinking water,a number of assumptions must be made.These include: (1) that the studypopulations selected for each of thecancer epidemiology studies arereflective of the entire population thatdevelops bladder cancer; (2) that thepercentage of those cancer cases in thestudies exposed to chlorinated drinkingwater are reflective of the bladdercancer cases in the U.S.; (3) that DBPswere the only carcinogens in thesechlorinated surface waters; and (4) thatthe relationship between DBPs inchlorinated drinking water exposureand bladder cancer is causal.

The last of these assumptions isperhaps the most open to question. Asnoted in the March 1998 NODA, theresults of the studies are inconsistent. In

light of these concerns, the Agencyagrees that causality between exposureto chlorinated water and bladder cancerhas not been established and that thenumber of cases attributable to suchexposures could be zero.

Based on the estimate of 54,500 newbladder cancer cases per year nationally,as projected by the National CancerInstitute for 1997, the numbers ofpossible bladder cancer cases per yearpotentially associated with exposures toDBPs in chlorinated drinking waterestimated from the five studies rangefrom 1,100 (0.02 × 54,500) to 9,300 (.17× 54,500) cases. As noted above, due tothe uncertainty in these estimates, thenumber of cases could also be zero. Inmaking these estimates it is necessary toassume that these bladder cancer casesare attributed to DBPs in chlorinatedsurface water, even though the studiesexamined the relationship betweenchlorinated surface water and bladdercancer. This derived range is notaccompanied by confidence intervals(C.Is), but the C.Is. are likely to be verywide. EPA believes that the mean riskestimates from each of the five studiesprovides a reasonable estimate of thepotential range of risk suggested by thedifferent epidemiological studies. TableIV–8 contains a summary of the riskestimates from the 1994 draft RIA andthe estimates derived from the morerecent analysis.

A related analysis based on oddsratios was conducted to derive a rangeof plausible estimates for cancerepidemiologic studies (EPA, 1998n).This analysis was also based on bladdercancer studies (the five studies citedabove in addition to Doyle et al. 1997).For the purpose of this exercise, theannual U.S. expected number of 47,000bladder cancers cited by Morris etal.(1992) was used to calculate estimatesof the cancers prevented. The number ofcancers attributable to DBP exposurewas estimated not to exceed 2,200–9,900 per year and could include zero.As would be expected from relatedanalysis performed in the same data,this range is similar to the 1,100–9300PAR range. EPA has used the 1100–9300PAR range for the RIA.

TABLE IV–8.—NUMBER OF CANCER CASES ATTRIBUTABLE TO DBPS: COMPARISON OF ESTIMATES IN 1994 AND 1998

1994 estimates 1998 estimates

Number of New Bladder Cancer Cases/Year ..................................... Approx. 50,000 ................... 54,500.Number of Estimated Deaths Due to Bladder Cancer/Year ............... Did not state ....................... 12,500.

Attributable to DBPs in Drinking WaterData Source ........................................................................................ >15 studies ......................... 5 studies that meet specific criteria.Causality .............................................................................................. No ....................................... No.Percent Attributable to DBPs .............................................................. Did not state ....................... 2% to 17%.


TABLE IV–8.—NUMBER OF CANCER CASES ATTRIBUTABLE TO DBPS: COMPARISON OF ESTIMATES IN 1994 AND 1998—Continued

1994 estimates 1998 estimates

Number of Cancer Cases Attributable to DBPs:Estimated Using Toxicological Data ............................................ Less than 1* ....................... Zero to 100.**Estimated Using Epidemiological Data ........................................ Over 10,000*** ................... Zero to 9,300.****

* Based on maximum likelihood estimates of risk from THMs.** Based on IRIS 95th percent C.I. estimates of risk from THMs.*** Indicates rectal and bladder cancer cases.**** Indicates only bladder cancer cases.

The current benefits analysis isstructured in roughly the same manneras that presented in the 1994 RIA. Thebaseline cancer risks could lie anywherefrom zero to 100 cases per year based ontoxicological data; and zero to 9,300cases per year based on epidemiologicaldata. Consequently, the task is to assessthe economic benefit of the final Stage1 DBPR in the face of this broad rangeof possible risk.

4. Exposure Reduction Analysis

EPA predicted exposure reductionsdue to the current Stage 1 DBPR relativeto the present baseline. EPA used theconcentration of TTHMs as a marker tomeasure the exposure to the range ofDBPs because data are available on thebaseline occurrence and formation ofTTHMs. There are limited data on thetotal mix of byproducts in drinkingwater. Therefore, the reduction inTTHMs is assumed to reflect thereduction in exposure to all DBPs. Todetermine the change in exposure, it isnecessary to estimate the pre-Stage 1baseline average TTHM concentrationand the post Stage 1 average TTHMconcentration. The difference in the pre-and post-Stage 1 TTHM concentrationsreflect the potential reduction inTTHMs and thus in DBPs.

As described previously, theestimated pre-Stage 1 TTHM weightedaverage concentration is 44 µg/L for allsystem sizes and types of systems. Thepost Stage 1 TTHM concentrations foreach system category were estimatedbased on the technology complianceforecasts previously discussed andestimated reductions in TTHM levelsdepending upon technology. The post-Stage 1 TTHM weighted averageconcentration is estimated at 33 µg/L.This represents a 24 percent reductionin TTHM levels resulting from the Stage1 DBPR. Further details of the aboveanalysis is described in the RIA for theStage 1 DBPR (USEPA, 1998g).

5. Monetization of Health Endpoints

The range of potential benefits fromthe Stage 1 DBPR can be estimated byapplying the monetary values for fatal

and nonfatal bladder cancer cases withthe estimate of the number of bladdercancer cases reduced by the rule. Thefollowing assumptions are used toestimate the range of potential benefits:

• An estimate of the number ofbladder cancer cases attributable toDPBs in drinking water ranging from 0to 9,300 annually.

• A 24 percent reduction in exposureto TTHMs due to the Stage 1 DBPR (75percent CI of 19 to 30 percent) willresult in an equivalent reduction inbladder cancer cases

• A value per statistical life saved forfatal bladder cancers represented by adistribution with a mean of $5.6 million

• A willingness to pay to avoid anonfatal case of bladder cancerrepresented by a distribution with amean of $587,500

Using the low end of the risk range of0 bladder cancer cases attributable toDBPs results in a benefits estimate of $0.To calculate the high end of the range,the 9,300 estimate of attributable casesis multiplied by the percent reductionin exposure to derive the number ofbladder cancer cases reduced (9,300 ×.24 = 2,232 bladder cancer casesreduced). This assumes a linearrelationship between reduction inTTHMs concentrations and reduction incancer risk (e.g., 24 percent reduction inTTHMs concentration is associated witha 24 percent reduction in cancer risk).Assuming 23 percent of the bladdercancer cases end in fatality and 77percent are nonfatal, the number of fatalbladder cancer cases reduced is 513(2,232 × .23) and the number of nonfatalbladder cancer cases is 1,719 (2,232 ×.77). Based on the valuationdistributions described above, theestimate of benefits at the meanassociated with reducing these bladdercancer cases is approximately $4 billion.It should be noted that these estimatesdo not include potential benefits fromreducing other health effects (e.g, colon/rectal cancer and reproductiveendpoints) that cannot be quantified atthis time. As a result, EPA believes thatthe potential benefits discussed intoday’s rule may be a substantial

underestimate of potential benefits thatwill be realized as a consequence oftoday’s action. While the low end of therange cannot extend below $0, it ispossible that the high end of the rangecould extend beyond $4 billion if theother reductions in risk could bequantified and monetized. No discountfactor has been applied to thesevaluations, although there is likely to bea time lag between compliance with therule and the realization of benefits.

Given this wide range of potentialbenefits and the uncertainty involved inestimating the risk attributable to DBPs,EPA undertook five differentapproaches to assessing the net benefitsof the Stage 1 DBPR. These approachesare described in the net benefits sectionand should be considered bothindividually and in the aggregate.

E. Net Benefits Analysis

The potential economic benefits of theStage 1 DBPR derive from the increasedlevel of public health protection andassociated decreased level of risk. Thequantification of the benefits resultingfrom DBP control is complicated by theuncertainty in the understanding of thehealth risks. Epidemiological studies,referred to previously, suggest anassociation between bladder cancer andexposure to chlorinated surface water;however, these risks are uncertain. Thelowest estimate in the selectedepidemiological studies of the numberof new bladder cancer cases per yearattributable to chlorinated surface wateris 1,100 cases, while the highest is 9,300cases. EPA recognizes that while theserisks may be real, they also could bezero. Assessment of risks based only ontoxicological data for THMs, indicate amuch lower risk (2 cancer cases per yearat the most likely estimate, to about 100cases per year using the 95 percentconfidence level upper bound), butTHMs represent only a few of the manyDBPs in drinking water.

EPA explored several alternativeapproaches for assessing the benefits ofthe Stage 1 DBPR: Overlap of Benefitand Cost Estimates; Minimizing TotalSocial Losses; Breakeven Analysis;


Household Costs; and Decision-AnalyticModel. A summary of the analysis ofeach approach is presented below. Moredetailed descriptions are described inthe RIA (USEPA, 1998g).

Overlap of Benefit and Cost Estimates.One method to characterize net benefitsis to compare the relative ranges ofbenefits and costs. Conceptually, anoverlap analysis tests whether there isenough of an overlap between the rangeof benefits and the range of costs forthere to be a reasonable likelihood thatbenefits will exceed costs. In atheoretical case where the high end ofthe range of benefits estimates does notoverlap the low end of the range of costestimates, a rule would be difficult tojustify based on traditional benefit-costrationale.

For the Stage 1 DBPR, the overlapanalysis (Figures IV–1a and IV–1b)

show that there is substantial overlap inthe estimates of benefits and costs. Therange of quantified benefits extendsfrom zero to over $4 billion. The zeroend of the range of estimated benefitsrepresents the possibility that there isessentially no health benefit fromreducing exposure to DBPs. The otherend of the range assumes there are 9,300bladder cancer cases per yearattributable to DBPs and there is a 24percent annual reduction in exposurewith the promulgation of the rule,resulting in avoidance of 2,232 cases.Assuming that number of avoided cases,approximately 513 would have beenfatalities and would result in a costsavings of approximately $3 billion(each avoided fatality results in a costsavings of $5.6 million). Additionally,1,719 non-fatal cases avoided wouldresult in a cost savings of approximately

$1 billion (each avoided non-fatal caseresults in a cost savings of $0.6 million).The sum of the cost savings isapproximately $4 billion. The high endof the benefits range could potentiallybe higher if other health damages areavoided. The range of cost estimates issignificantly smaller, ranging from $500million to $900 million annually.Although these cost estimates haveuncertainty, the degree of uncertainty isof little consequence to the decisionsbeing made given the scale of theuncertainty for the benefits.

Figure IV–1b, on the other hand,indicates that while the quantifiedbenefits could exceed the costs, there isthe possibility that there could benegative net benefits if there were nohealth benefits.

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Figure IV–1a Overlap of EstimatedBenefits and Costs of the Stage 1 DBPR

Figure IV–1b Overlap of the Ranges ofthe Estimated Benefits and Costs of theStage 1 DBPR

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Minimizing Total Social LossesAnalysis. Minimizing Total SocialLosses analysis, sometimes called‘‘minimizing regrets’’ analysis, is adecision-aiding tool that is suited foruse in situations where it is impossibleto pin down the exact nature and extentof a risk. The basic premise ofMinimizing Total Social Losses analysisis to estimate total social costs for policyalternatives over a range of plausiblerisk scenarios. The actual, or ‘‘true’’ riskis unknowable, so instead this analysisasks what range and level of risks couldbe true, and then evaluates the totalcosts to society if particular risk levelswithin that range turned out to be the‘‘true’’ value. Total social costs includeboth the cost to implement the policyoption, plus costs related to residual(i.e., remaining) health damages at each

risk level after implementation of thepolicy option.

Under this analysis the ‘‘total socialcosts’’ (water treatment costs plus costsof health damages still remaining aftertreatment) are calculated for threeregulatory alternatives (No Action, Stage1, and Strong Intervention—otherwiseknown as the proposed Stage 2requirements of the 1994 proposal)across a range of risk scenarios (< 1; 100;1,000; 2,500; 5,000; 7,500; and 10,000attributable bladder cancer casesannually). Total social costs for eachregulatory alternative for different riskassumptions are presented in Table IV–9. The results indicate that the Stage 1DBPR has the least social cost amongthe three alternatives analyzed acrossthe range of risks from 2,500 through7,500 attributable bladder cancer casesannually.

Total ‘‘social loss’’ for each riskscenario are also indicated in Table IV–9. The ‘‘social loss’’ is the cost to societyof making a wrong choice among theregulatory alternatives. It is computed asthe difference between the total socialcost (water treatment cost plusremaining health damages) of analternative at a given risk scenario andthe total social cost of the bestalternative (least total social costalternative for that risk scenario). Theregulatory alternatives across thedifferent risk levels can also becompared to see which alternativeminimizes the maximum potential loss.The best alternative, by this ‘‘mini-max’’criteria, would be the one in which theupper bound of potential losses issmallest.



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Under the Stage 1 DBPR alternative,the worst loss that could happen wouldoccur if the lowest end of the risk rangeis true. This would result in total sociallosses of $0.7 billion per year. It isconcluded that the maximum potentialloss of the Stage 1 alternative is smallerthan that of No Action ($4.1 billion) bya factor of 6 and smaller than that ofStrong Intervention ($2.9 billion) by afactor of 4. Thus, the Stage 1 DBPR isthe best of the 3 alternatives atminimizing the maximum social loss.

The 1994 Reg. Neg. and 1997 M–DBPAdvisory Committees implicitly appliedthis type of ‘‘minimizing maximumloss’’ framework when developing andevaluating the DBP regulatory options.In the face of large uncertainty regardingrisk from DBPs, they decided that amoderate response, relying on the morecost-effective of the available treatmentmethods was appropriate as an interimstep until more information on riskbecomes available.

Break Even Analysis. Breakevenanalysis represents another approach toassessing the benefits of the Stage 1DBPR given the scientific uncertainties.Breakeven is a standard benchmark ofcost effectiveness and economicefficiency, and is essentially the pointwhere the benefits of the Stage 1 DBPRare equal to the costs. Normally, thebenefits and costs of an option arecalculated separately and thencompared to assess whether and bywhat amount benefits exceed costs. Inthe case of the Stage 1 DBPR,independently estimating benefits isdifficult, if not impossible, because ofthe 10,000-fold uncertainty surroundingthe risk. Instead, the breakeven analysisworks backwards from those variablesthat are less uncertain. In this case,implementation costs for the rule andthe monetary value associated with thehealth endpoints are used to calculatewhat baseline risk and risk reduction

estimates are needed in order for thebenefits, as measured in avoided healthdamages associated with bladder cancer,to equal the costs.

Two important concepts for thisanalysis are the cost of illness measureand the willingness-to-pay measure. Thecost of illness measure includes medicalcosts and lost wages associated withbeing unable to work as a result ofillness. In comparison, willingness-to-pay measures how much one would payto reduce the risk of having all thediscomfort and costs associated withnonfatal cancer if such an optionexisted. The main difference betweenthese two methods is that willingness-to-pay incorporates pain and suffering,as well as changes in behavior into thevaluation, while cost of illness does not.EPA has estimated the cost of a non-fatal case of bladder cancer at $121,000using the cost of illness method, and at$587,500 using the willingness-to-payapproach.

Assuming an annual cost of $701million and assumptions about themonetary value of preventing both fataland nonfatal bladder cancer cases, theStage 1 DBPR would need to reduce 438bladder cancer cases per year using thewillingness-to-pay measure for nonfatalcancers or 574 cases per year using thecost of illness measure. If exposure isreduced by 24 percent, the baselinenumber of bladder cancer casesattributable to DBPs in chlorinateddrinking water required to break evenwould need to range from 1,820 to 2,390new cases annually. Although thesevalues are well above the rangeindicated by existing toxicological datafor THMs alone, they fall within theattributable risk range suggested by theepidemiological studies.

Household Cost Analysis. A fourthapproach for assessing the net benefitsof the Stage 1 DBPR is to calculate thecosts per household for the rule.

Household costs provide a commonsense test of benefit/cost relationshipsand are another useful benchmark forcomparing the willingness-to-pay toreduce the possible risk posed by DBPsin drinking water. It is essentially ahousehold level breakeven analysis. Itworks backwards from the cost to askwhether the implied amount of benefits(willingness-to-pay) needed to covercosts is a plausible amount.

About 115 million households arelocated in service areas of systemsaffected by the Stage 1 DBPR. Of thesehouseholds, 71 million (62 percent) areserved by large surface water systems.Approximately 4.2 million (4 percent)are served by small surface watersystems. Large ground water systemsserved 24 million households (21percent) and small ground watersystems serve 15.7 million households(14 percent).

All of the households served bysystems affected by the Stage 1 DBPRwill incur some additional costs (e.g.,monitoring costs), even if the systemdoes not have to change treatment tocomply with the proposed rule. Thecosts calculated below include bothmonitoring and treatment costs.

The cumulative distribution ofhousehold costs for all systems and byeach system type is displayed in FiguresIV–2a, IV–2b, IV–2c. The distributionsshow that the large percentage ofhouseholds will incur small additionalcosts, with a small portion of systemsfacing higher costs. At the highest endof the distribution, approximately 1,400households served by surface watersystems in the 25–100 size rangeswitching to membrane technology willface an average annual cost increase of$400 per year ($33 per month).

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The households have been sorted intothree cost categories for the ease ofcomparison (Table IV–10). The firstcategory includes households with acost increase of less than $12 per year,less than $1 per month. The secondcategory contains households with costsgreater than $12 per year, but less than$120 per year ($10 per month). Thethird category includes households withcost increases greater than $120 per yearto $400 per year ($33 per month).

Across all system categories (seeFigure IV–2a), 95 percent of thehouseholds (110.1 million) fall withinthe first category and will incur lessthan $1 per month additional costs dueto the Stage 1 DBPR. An additional 4percent (4.4 million) are in the secondcategory at between $1 and $10 permonth cost increase and 1 percent (1.0

million) are in the highest category($10–$33.40 per month).

For households served by largesurface water systems (Figure IV–2b), 98percent will incur less than $1 permonth, 2 percent will incur between $1and $10 per month, and 0.03 percentwill incur greater than $10 per month.The highest cost ($125 annually, $10.40monthly) is faced by households servedby systems in the 10,000 to 25,000 sizerange implementing membranetechnology.

For households served by smallsurface water systems (Figure IV–2c), 71percent will incur less than $1 permonth, 28 percent will incur between$1 and $10 per month, and 1 percentwill incur greater than $10 per month.The highest cost ($400 annually, $33monthly) is faced by households servedby systems in the 25–100 size rangeimplementing membrane technology.

For households served by largeground water systems (Figure IV–2b), 95percent will incur less than $1 permonth, 4 percent will incur between $1and $10 per month, and 1 percent willincur greater than $10 per month. Thehighest cost ($125 annually, $10.40monthly) is faced by households servedby systems in the 10,000 to 25,000 sizerange implementing membranetechnology.

For households served by smallground water systems (Figure IV–2c), 91percent will incur less than $1 permonth, 5 percent will incur between $1and $10 per month, and 4 percent willincur greater than $10 per month. Thehighest cost ($357 annually, $29.75monthly) is faced by households servedby systems in the 25–100 size rangeimplementing membrane technology.



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In the small proportion of systemswhere household costs are shown to bemuch greater—up to several hundredsof dollars per year—these results aredriven by the assumption thatmembrane technologies will be theselected treatment, as noted above.Additionally, two points must be made:(1) a number of these systems may findless expensive means of compliance(e.g., selection of alternative sourcewater, purchased water, orconsolidation with other systems); and(2) if these systems do installmembranes, they may receive additionalwater quality and/or compliancebenefits beyond those associated withDBPs. For example, because membranesare so effective, systems that installmembranes are likely to incur lowercompliance costs for futurerulemakings.

Given the uncertain nature of the risksassociated with DBPs, household costsprovide a common sense estimate ofwillingness-to-pay to reduce the risks:Would the average household (95percent of households) be willing to payless than $1 per month ($12 per year) toreduce the potential risks posed byDBPs?

Willingness to pay studies are notavailable to directly answer thisquestion. Taking the $1 per monthfigure as a measure of implied publichealth benefit at the household level, itis useful to ask what benefits can beidentified that could balance a $1 permonth expenditure. First, it is entirelypossible that there is much more than adollar-a-month’s worth of tangiblehealth benefit based on reduced risk ofbladder cancer alone. Second, the broadexposure to DBPs and the possiblehealth effects involved offer thepossibility that there are significantadditional health benefits of a tangiblenature. However, the agency recognizesthat in the small percentage of situationswhere the costs per household isbetween $120 to $400 per year, this mayindeed be a difficult financial burden tomeet (e.g., may exceed householdwillingness-to-pay).

Finally, the preventive weighing andbalancing of public health protectionalso provides a margin of safety—ahedge against uncertainties. Recentsurvey research conducted in thedrinking water field providescompelling empirical evidence that thenumber one priority of water systemcustomers is the safety of their water.Although definitive economic researchhas not been performed to investigatethe extent of household willingness-to-pay for such a margin of safety, there isstrong evidence from conventional

customer survey research implying ademand for this benefit.

Decision Analytical model. The RIAalso discusses a fifth type of analysis inwhich probability functions are used tomodel the uncertainty surroundingthree variables (rule cost, exposurereduction, and attributable bladdercancer risk) in order to derive aprobability distribution function forannual net benefit of the Stage I rule.Because there is little actual data onthese probability functions, thisapproach should be consideredillustrative only. It is not discussedfurther here, but is discussed in Chapter6 of the RIA for the Stage 1 DBPR (EPA,1998g).

While any one of the above analyticalapproaches by itself may not make adefinitive case for the benefit-costeffectiveness for the Stage 1 DBPR,taken collectively EPA believes theyindicate that the Stage 1 DBPR benefitsto society will exceed the costs. Themonetized benefits in the fivealternatives represent only a portion oftotal potential benefits. Benefitsassociated with other cancer sites (rectaland colon) and other health endpoints(such as developmental andreproductive effects) could not bequantified at this time, and while theycould be nil, they also could be quitelarge. Based on a careful weighing of theprojected costs against the potentialquantified and non-quantified benefits,EPA has determined that the benefits ofthe rule justify its costs.

F. Summary of CommentsMany commenters expressed concern

about the wide range of benefits giventhe high national cost of the rule. EPAhas revised the benefits analysis; andwhile the associated uncertaintiesremain large, EPA believes the benefitsof the Stage 1 DBPR justify its costs.

Other commenters expressed concernwith using the data from Morris et al.(1992) for quantifying benefits. Theybelieved that the studies used in themeta-analysis were different in designand thus not appropriate to use in meta-analysis. In addition the commentersbelieved that potential confoundingfactors or bias may not have beenadequately controlled in the selectedstudies. Others believed there wasutility in using the meta-analysis toprovide a perspective on the potentialcancer risks. Several commenters weresupportive of the Poole (1997)evaluation of the Morris et al. (1992)meta-analysis stating that theyconcurred that the Morris analysisshould not be used for estimatingbenefits for the Stage 1 DBPR. Othercommenters suggested a better use of

the resources used to complete thePoole report would have been tocomplete a new meta-analysis using themore recent studies that have come outsince the Morris et al. (1992) meta-analysis and that the Poole evaluationdid not advance the science in this area.Several commenters were critical of thePAR analysis (described in EPA, 1998a)used to characterize the potentialbaseline bladder cancer cases per yearthat could be attributable to exposure tochlorinated drinking water. Theypresent several arguments including:questioning whether such an analysis iswarranted given the inconsistencies inthe studies used to complete theanalysis; stating that the use of the termupper bound of any suggested risk ofcancer is inappropriate because thisdoes not include the potential risks fromother cancer sites such as colon andrectal; using the assumption of causalityis not warranted given theinconsistencies in the studies used tocomplete the PAR analysis; and the PARanalysis should include a lower boundestimate of zero.

EPA agrees that the use of the Morriset al. (1992) meta-analysis for estimatingbenefits is not appropriate for thereasons cited by commenters (e.g.,studies of different designs anddiscussed in more detail in the 1998DBP NODA). EPA is currentlyconsidering whether a new meta-analysis that uses the most recentepidemiology studies would be usefulfor the Stage 2 rulemaking. The Poole(1997) report considered a meta analysisof the available data. Poole used severaltechniques to evaluate the data andincluded several new studies that wereavailable at the time of his analysis.Poole concluded that the cancerepidemiology data considered in hisevaluation should not be combined intoa single summary estimated and that thedata had limited utility for riskassessment purposes. More recentstudies by Cantor et al. (1998), Doyle etal. (1997) and Freedman et al. (1997)were not available at the time of hisevaluation.

EPA understands commentersconcerns with the PAR analysis,especially concerns with assuming‘‘causality’’ in the PAR evaluation whenit is stated in other sections of thepreamble that EPA does not believecausality has been established. Eventhough causality has not beenestablished, EPA is required to estimatethe potential impacts of majorregulations such as the DBP Stage 1rule. The Agency believes it isappropriate to conduct the PAR analysisas described in the 1998 DBP NODA(EPA, 1998a), to provide estimates of the


potential risk that may need to bereduced. EPA agrees that the use of theterm ‘‘upper bound of any suggestedrisk’’ is not appropriate because thereare other potential risks that have notbeen quantified that may contribute tothe overall risk estimates. In addition,EPA agrees that the estimates of thepotential cancer cases should includezero as this is a possibility given theuncertainties in the data. EPA agreesthat several assumptions are made inthe analysis regarding the nationalextrapolation of the results and thatthere is insufficient information at thistime to validate these assumptions.However, given the need to developnational estimates of risk, EPA believesit is appropriate to make theseassumptions in order to provide aperspective on the potential risks fromexposure to chlorinated surface waters.

Commenters expressed concerns withthe high costs associated with systemsthat must adopt alternative advancedtechnologies, especially for smallsystems. Since the 1994 proposal, theprojected national costs for the Stage 1DBPR have dropped significantly (asdiscussed above). This is mainly due tothe revised compliance forecast andlower membrane technology costs. Inthe revised compliance forecast, fewersystems using surface water will needadvanced technologies to comply. Thisshift to lesser use of advancedtechnologies to comply with the Stage 1DBPR also pertains to small systems(those serving less than 10,000 people).

Commenters expressed concern forthe high costs associated with the Stage2 DBPR and whether EPA would obtainenough information to adequatelyunderstand the risks that might beavoided to justify such a rule. EPAagrees that additional health effectsinformation is needed beforereproposing the Stage 2 DBPR and willaddress this issue in the next round ofFACA deliberations. Based on new datagenerated through research, EPA willreevaluate the Stage 2 regulations andre-propose, as appropriate.

V. Other Requirements

A. Regulatory Flexibility Act

1. Today’s RuleUnder the Regulatory Flexibility Act,

5 U.S.C. 601 et seq. (RFA), as amendedby the Small Business RegulatoryEnforcement Fairness Act, EPAgenerally is required to conduct aregulatory flexibility analysis describingthe impact of the regulatory action onsmall entities as part of rulemaking.However, under section 605(b) of theRFA, if EPA certifies that the rule willnot have a significant economic impact

on a substantial number of smallentities, EPA is not required to preparea regulatory flexibility analysis.

Throughout the 1992–93 negotiatedrulemaking process for the Stage 1DBPR and IESWTR and in the July 1994proposals for these rules, a small PWSwas defined as a system serving fewerthan 10,000 persons. This definitionreflects the fact that the original 1979standard for total trihalomethanesapplied only to systems serving at least10,000 people. The definition thusrecognizes that baseline conditions fromwhich systems serving fewer than10,000 people will approachdisinfection byproduct control andsimultaneous control of microbialpathogens is different than that forsystems serving 10,000 or more persons.EPA again discussed this approach tothe definition of a small system for theserules in the 1998 DBP NODA (EPA,1998a). EPA is continuing to define‘‘small system’’ for purposes of this ruleand the IESWTR as a system whichserves fewer than 10,000 people.

The Agency has since proposed andtaken comment on its intent to define‘‘small entity’’ as a public water systemthat serves 10,000 or fewer persons forpurposes of its regulatory flexibilityassessments under the RFA for all futuredrinking water regulations. (SeeConsumer Confidence Reports Rule, 63FR 7620, Feb. 13, 1998.) In thatproposal, the Agency discussed thebasis for its decision to use thisdefinition and to use a single definitionof small public water system whetherthe system was a ‘‘small business’’,‘‘small nonprofit organization’’, or‘‘small governmental jurisdiction.’’ EPAalso consulted with the Small BusinessAdministration on the use of thisdefinition as it relates to smallbusinesses. Subsequently, the Agencyhas used this definition in developingits regulations under the Safe DrinkingWater Act. This approach is virtuallyidentical to the approach used in theStage 1 DBPR and IESWTR. Since, EPAis not able to certify that the final Stage1 DBPR will not have a significanteconomic impact on a substantialnumber of small entities, EPA hascompleted a final RFA and will publisha small entity compliance guidance tohelp small entities comply with thisregulation.

2. Background and AnalysisThe Regulatory Flexibility Act

requires EPA to address the followingwhen completing a final RFA: (1) statesuccinctly the objectives of, and legalbasis for, the final rule; (2) summarizepublic comments on the initial RFA, theAgency’s assessment of those

comments, and any changes to the rulein response to the comments; (3)describe, and where feasible, estimatethe number of small entities to whichthe final rule will apply; (4) describe theprojected reporting, record keeping, andother compliance requirements of therule, including an estimate of the classesof small entities that will be subject tothe requirements and the type ofprofessional skills necessary forpreparation of reports or records; and (5)describe the steps the Agency has takento minimize the impact on smallentities, including a statement of thereasons for selecting the chosen optionand for rejecting other options whichwould alter the impact on small entities.EPA has considered and addressed allthe above requirements in theRegulatory Impact Analysis (RIA) for theStage 1 DBPR (EPA 1998g). Thefollowing is a summary of the RFA.

The first requirement is discussed insection I of today’s rule. The second,third and fifth requirements aresummarized below. The fourthrequirement is discussed in V.B(Paperwork Reduction Act) and theInformation Collection Requirement.

Number of Small Entities Affected.EPA estimates that 69,491 groundwatersystems will be affected by the Stage 1DBPR, with 68,171 (98%) of thesesystems serving less than 10,000persons. Of the 68,171 small systemsaffected, EPA estimates that 8,323 (12%)will have to modify treatment to complywith the Stage 1 DBPR. Of these, 5,403systems (8%) will use chloramines tocomply and 2,921 systems (4.3%) willuse membranes to comply. Use of thesetechnologies by small groundwatersystems will result in total capital costsof $998 million and an annualizedtreatment cost of $180 million.

EPA estimates that 6,560 surfacewater systems will be affected by theStage 1 DBPR, with 5,165 (79%) of thesesystems serving less than 10,000persons. It is estimated that 3,616 (70%)of these small systems will have tomodify treatment to comply with theStage 1 DBPR and 3,459 (67%) of thesesystems will use a combination ofenhanced coagulation, chloramines, andozone, while another 157 systems (3%)will use membranes. Use of thesetechnologies by small surface watersystems will result in total capital costsof $243 million and an annualizedtreatment cost of $46 million.

EPA has included several provisionswhich will reduce the economic burdenof compliance for these small systems.These requirements, discussed ingreater detail in the RIA (EPA, 1998g),include:


—Less routine monitoring. Smallsystems are required to monitor lessfrequently for such contaminants asTTHMs and HAA5. Also, groundwater systems (the large majority ofsmall systems) are required to monitorless frequently than Subpart Hsystems (surface water systems andgroundwater under the directinfluence of surface water) of thesame size.

—Extended compliance dates. Systemsthat use only ground water not underthe direct influence of surface waterserving fewer than 10,000 people have60 months from promulgation of thisrule to comply. This is in contrast tolarge Subpart H systems which have36 months to comply. These extendedcompliance dates will allow smallersystems to learn from the experienceof larger systems on how to most costeffectively comply with the Stage 1DBPR. In addition, larger systems willgenerate a significant amount oftreatment and cost data from the ICRand in their efforts to achievecompliance with the Stage 1requirements. EPA intends tosummarize this information and makeit available through guidance manuals(i.e., the Small Entities GuidanceManual). EPA believes thisinformation will assist smallersystems in achieving compliance withthe Stage 1 DBPR.

3. Summary of CommentsSeveral commenters expressed

concern with the significant economicburden that the Stage 1 DBPR wouldplace on small systems. Othercommenters suggested more flexibilitybe given for small systems and that alonger compliance period for smallsystems should be included in the finalStage 1 DBPR. Several commenterssuggested small systems should not beincluded in the final Stage 1 DBPRbecause the costs for implementing therule would exceed the potential benefitsfor these systems.

EPA understands commenters’concerns with the potential significanteconomic burden on small systems.Because of this potential significantimpact, EPA has provided severalrequirements which will reduce theburden on these systems. Theserequirements which are discussed aboveand also in greater detail in the RIA(EPA, 1998g) include: (1) less routinemonitoring; and (2) extendedcompliance dates. EPA also believessmall systems can reduce theireconomic burden by; (1) consolidationwith larger systems; (2) using moneyfrom the State revolving fund loans; and(3) using variances and exemptions

when needed. EPA considered anoption in the development of the finalrule for large systems to have MCLs of80 ug/L for TTHMs and 60 ug/L forHAAs and for small systems to have asimple TTHM standard of 100 ug/L.This option was rejected becauseallowing small systems to comply witha different MCL level would notadequately protect the health of thepopulation served by these systems.EPA did not consider excluding smallsystems from the Stage 1 DBPR, becausethese systems do not currently have anystandards for DBPs and the Agencybelieved there was a public healthconcern that needed to be addressed.For a more detailed description of thealternatives considered in thedevelopment of the final rule see thefinal RIA (EPA, 1998g) or the finalUnfunded Mandates Reform ActAnalysis for the Stage 1 DBPR (EPA,1998o).

B. Paperwork Reduction ActThe Office of Management and Budget

(OMB) has approved the informationcollection requirements contained inthis rule under the provisions of thePaperwork Reduction Act, 44 U.S.C.3501 et seq. and has assigned OMBcontrol number 2040–0204.

The information collected as a resultof this rule will allow the States and theEPA to evaluate PWS compliance withthe rule. For the first three years afterpromulgation of the Stage 1 DBPR, themajor information requirements pertainto preparation for monitoring activities,and for compliance tracking. Responsesto the request for information aremandatory (Part 141). The informationcollected is not confidential.

EPA is required to estimate theburden on PWS for complying with thefinal rule. Burden means the total time,effort, or financial resources expendedby persons to generate, maintain, retain,or disclose or provide information to orfor a Federal agency. This includes thetime needed to review instructions;develop, acquire, install, and utilizetechnology and systems for the purposesof collecting, validating, and verifyinginformation, processing andmaintaining information, and disclosingand providing information; adjust theexisting ways to comply with anypreviously applicable instructions andrequirements; train personnel to be ableto respond to a collection ofinformation; search data sources;complete and review the collection ofinformation; and transmit or otherwisedisclose the information.

EPA estimates that the annual burdenon PWS and States for reporting andrecordkeeping will be 314,471 hours.

This is based on an estimate that therewill be 4,631 respondents on averageper year who will need to provide about9,449 responses and that the averageresponse will take 33 hours. The annuallabor cost is estimated to be about $12million. In the first 3 years afterpromulgation of the rule, only laborcosts are incurred. The costs areincurred for the following activities:reading and understanding the rule;planning; and training.

An Agency may not conduct orsponsor, and a person is not required torespond to a collection of informationunless it displays a currently valid OMBcontrol number. The OMB controlnumbers for EPA’s regulations are listedin 40 CFR Part 9 and 48 CFR Chapter15. EPA is amending the table in 40 CFRPart 9 of currently approved ICR controlnumbers issued by OMB for variousregulations to list the informationrequirements contained in this finalrule. This ICR was previously subject topublic notice and comment prior toOMB approval. As a result, EPA findsthat there is ‘‘good cause’’ under section553 (b)(B) of the AdministrativeProcedures Act (5 U.S.C. 553 (b) (B)) toamend this table without prior noticeand comment. Due to the technicalnature of the table, further notice andcomment would be unnecessary.

C. Unfunded Mandates Reform Act

1. Summary of UMRA Requirements

Title II of the Unfunded MandatesReform Act of 1995 (UMRA), PublicLaw 104–4, establishes requirements forFederal agencies to assess the effects oftheir regulatory actions on State, local,and tribal governments and the privatesector. Under UMRA section 202, EPAgenerally must prepare a writtenstatement, including a cost-benefitanalysis, for proposed and final ruleswith ‘‘Federal mandates’’ that mayresult in expenditures to State, local,and tribal governments, in the aggregate,or to the private sector, of $100 millionor more in any one year. Beforepromulgating an EPA rule, for which awritten statement is needed, section 205of the UMRA generally requires EPA toidentify and consider a reasonablenumber of regulatory alternatives andadopt the least costly, most cost-effective or least burdensome alternativethat achieves the objectives of the rule.The provisions of section 205 do notapply when they are inconsistent withapplicable law. Moreover, section 205allows EPA to adopt an alternative otherthan the least costly, most cost effectiveor least burdensome alternative if theAdministrator publishes with the final


rule an explanation on why thatalternative was not adopted.

Before EPA establishes any regulatoryrequirements that may significantly oruniquely affect small governments,including tribal governments, it musthave developed, under section 203 ofthe UMRA, a small government agencyplan. The plan must provide fornotification to potentially affected smallgovernments, enabling officials ofaffected small governments to havemeaningful and timely input in thedevelopment of EPA regulatoryproposals with significant Federalintergovernmental mandates; andinforming, educating, and advisingsmall governments on compliance withthe regulatory requirements.

2. Written Statement for Rules WithFederal Mandates of $100 Million orMore

EPA has determined that this rulecontains a Federal mandate that mayresult in expenditures of $100 million ormore for State, local, and tribalgovernments, in the aggregate, and theprivate sector in any one year.Accordingly, EPA has prepared, undersection 202 of the UMRA, a writtenstatement addressing the followingareas: (1) authorizing legislation; (2)cost-benefit analysis including ananalysis of the extent to which the coststo State, local and Tribal governmentswill be paid for by the federalgovernment; (3) estimates of futurecompliance costs and disproportionatebudgetary effects; (4) macro-economiceffects; and (5) a summary of EPA’sconsultation with State, local, andTribal governments, and a summary oftheir concerns, and a summary of EPA’sevaluation of their concerns. A moredetailed description of this analysis ispresented in EPA’s Unfunded MandatesReform Act Analysis for the Stage 1 DBPRule (EPA, 1998o) which is included inthe docket for this rule.

a. Authorizing Legislation. Today’srule is promulgated pursuant to Section1412(b)(2) of the 1996 amendments tothe SDWA; paragraph C of this sectionestablishes a statutory deadline ofNovember 1998 to promulgate this rule.This rule supersedes the TTHM Rule(EPA, 1979). In addition, the Stage 1DBP rule is closely integrated with theIESWTR, which also has a statutorydeadline of November 1998.

b. Cost Benefit Analysis. Section IVdiscusses the cost and benefitsassociated with the Stage 1 DBP rule.Also, the EPA’s Regulatory ImpactAnalysis of the Stage 1 Disinfectants/Disinfection Byproducts Rule (EPA,1998g) contains a detailed cost benefitanalysis. Today’s rule is expected tohave a total annualized cost ofapproximately $701 million using a 7percent cost of capital. The analysisincludes both qualitative and monetizedbenefits for improvements to health andsafety. Because of scientific uncertaintyregarding the exposure assessment andthe risk assessment for DBPs, theAgency has used five analyticalapproaches to assess the benefits of theStage 1 DBP. These analyses were basedon the quantification of bladder cancerhealth damages avoided. However, thisrule may also reduce colon and rectalcancers, as well as decrease adversereproductive and developmental effects.This would further increase the benefitsof this rule.

Various Federal programs exist toprovide financial assistance to State,local, and Tribal governments incomplying with this rule. The Federalgovernment provides funding to Statesthat have primary enforcementresponsibility for their drinking waterprograms through the Public WaterSystems Supervision Grants program.Additional funding is available fromother programs administered either byEPA or other Federal agencies. Theseinclude the Drinking Water StateRevolving Fund (DWSRF) and Housingand Urban Development’s CommunityDevelopment Block Grant Program. Forexample, SDWA authorizes theAdministrator of the EPA to awardcapitalization grants to States, which inturn can provide low cost loans andother types of assistance to eligiblepublic water systems. The DWSRFassists public water systems withfinancing the costs of infrastructureneeded to achieve or maintaincompliance with SDWA requirements.Each State will have considerableflexibility to determine the design of itsprogram and to direct funding towardits most pressing compliance and publichealth protection needs. States mayalso, on a matching basis, use up to tenpercent of their DWSRF allotments for

each fiscal year to assist in running theState drinking water program.

c. Estimates of Future ComplianceCosts and Disproportionate BudgetaryEffects. To meet the UMRA requirementin section 202, EPA analyzed futurecompliance costs and possibledisproportionate budgetary effects. TheAgency believes that the cost estimates,indicated above and discussed in moredetail in Section IV of this rule,accurately characterize futurecompliance costs of the rule.

In regard to the disproportionateimpacts, EPA considered available datasources in analyzing thedisproportionate impacts upongeographic or social segments of thenation or industry. This analysis wasdifficult because impacts will mostlikely depend on a system’s sourcewater characteristics and this data is notavailable for all systems. However, itshould be noted that the rule uniformlyprotects the health of all drinking watersystem users regardless of the size ortype of system. Further analysisrevealed that no geographic or socialsegment patterns were likely for thisrule. One observation is that thehistorical pattern of development in thiscountry led most large cities to bedeveloped near rivers and other bodiesof water useful for power,transportation, and drinking water. Tothe extent that this rule affects surfacewater, it in most ways reflects thedistribution of population andgeography of the nation. No rationale fordisproportionate impacts by geographyor social segment was identified. Thisanalysis, therefore, developed threeother measures: reviewing the impactson small systems versus large systems;reviewing the costs to public versusprivate water systems; and reviewingthe household costs of the final rule.

First, the national impacts on smallsystems (those serving fewer than10,000 people) versus large systems(those serving 10,000 people or more) isindicated in Table V–1. The higher costto the small ground water systems ismostly attributable to the large numberof these types of systems (i.e. there are68,171 small ground water systems,1,320 large ground water systems, 5,165small surface water systems, and 1,395large surface water surface watersystems).

TABLE V–1.—ANNUAL COST OF COMPLIANCE FOR SMALL AND LARGE SYSTEMS ($000)*

Small systems(population< 10,000)

Large systems(population≥ 10,000)

Surface Water Systems (All) .................................................................................................................................... $56,804 $278,321


TABLE V–1.—ANNUAL COST OF COMPLIANCE FOR SMALL AND LARGE SYSTEMS ($000)*—Continued

Small systems(population< 10,000)

Large systems(population≥ 10,000)

Ground Water System (All) ...................................................................................................................................... 218,062 130,651

Total .................................................................................................................................................................. 274,866 408,972

* Costs calculated at a 7 percent cost of capital and include one time start-up costs.

The second measure ofdisproportionate impact evaluated is therelative total costs to public versusprivate water systems, by size. EPAbelieves the implementation of the ruleaffects both public and private watersystems equally, with the variance intotal cost by system size merely afunction of the number of affectedsystems.

The third measure, household costs,can also be used to gauge the impact ofa regulation and to determine whetherthere are disproportionately highimpacts in particular segments of thepopulation. A detailed analysis ofhousehold cost impacts by system sizeand system type are presented inSection IV.E. In summary, for largesurface water systems EPA estimatesthat 98 percent of households will incurcosts of less than $1 per month while0.3 percent of households will incurcosts greater than $10 per month. Forlarge groundwater systems, EPAestimates that 95 percent of householdswill incur costs of less than $1 permonth while 1.0 percent of householdswill incur costs greater than $10 permonth. For small surface water systemsEPA estimates the 71 percent ofhouseholds will incur costs of less than$1 per month while 1 percent ofhouseholds will incur costs of greaterthan $10 per month. For smallgroundwater systems EPA estimates that91 percent of households will incurcosts of less than $1 per month while 4percent of households will incur costsof greater than $10 per month.

The household analysis tends tooverestimate the costs per householdbecause of the structure andassumptions of the methodology. Forexample, the highest per-household costwould be incurred in a system usingmembrane technology. These systems,conversely, might seek less costlyalternatives such as point-of-usedevices, selection of alternative watersources, or connecting into a largerregional water system. The overall effectis that costs are higher in smallersystems, and a higher percentage ofthose systems are publicly owned.Smaller systems, however, represent alarger portion of systems that are not in

compliance with existing regulations.EPA believes that smaller systemsincurring the highest household costsmay also incur the highest reduction inrisk. This is because smaller systemshave not had to previously comply witha TTHMs standard of 100 ug/L. In theRIA, EPA estimates that on average,small systems will achieve about twiceas much reduction in risk as achievedby larger systems (EPA,1998g).

Based on the analysis above, EPAdoes not believe there will bedisproportionate impacts on smallsystems, public versus private systems,or generally by household. A moredetailed description of this analysis ispresented in the EPA’s UnfundedMandates Reform Act Analysis for theStage 1 DBP Rule (EPA,1998o).

d. Macro-economic Effects. Asrequired under UMRA Section 202, EPAis required to estimate the potentialmacro-economic effects of theregulation. Macro-economic effects tendto be measurable in nationwideeconometric models only if theeconomic impact of the regulationreaches 0.25 percent to 0.5 percent ofGross Domestic Product (GDP). In 1997,real GDP was $7,188 billion so a rulewould have to cost at least $18 billionto have a measurable effect. A regulationwith a smaller aggregate effect isunlikely to have any measurable impactunless it is highly focused on aparticular geographic region oreconomic sector. The macro-economiceffects on the national economy fromthe Stage 1 DBPR should be negligiblebased on the fact that the total annualcosts are about $701 million per year (ata 7 percent cost of capital) and the costsare not expected to be highly focused ona particular geographic region or sector.

e. Summary of EPA’s Consultationwith State, Local, and TribalGovernments and Their Concerns.Under UMRA section 202, EPA is toprovide a summary of its consultationwith elected representatives (or theirdesignated authorized employees) ofaffected State, local and Tribalgovernments in this rulemaking.Although this rule was proposed beforeUMRA became a statutory requirement,EPA initiated consultations with

governmental entities and the privatesector affected by this rule throughvarious means. This includedparticipation on a RegulatoryNegotiation Committee chartered underthe Federal Advisory Committee Act(FACA) in 1992–93 that includedstakeholders representing State andlocal governments, public healthorganizations, public water systems,elected officials, consumer groups, andenvironmental groups.

After the amendments to SDWA in1996, the Agency initiated a secondFACA process, similarly involving abroad range of stakeholders, and heldmeetings during 1997 to address theexpedited deadline for promulgation ofthe Stage 1 DBPR in November 1998.EPA established the M–DBP AdvisoryCommittee to collect, share, and analyzenew data reviewed since the earlier Reg.Neg. process and also to build aconsensus on the regulatoryimplications of this new information.The M–DBP Advisory Committeeestablished a technical working group toassist them with the many scientificissues surrounding this rule. TheCommittee included representativesfrom organizations such as the NationalLeague of Cities, the NationalAssociation of City and County HealthOfficials, the Association ofMetropolitan Water Agencies, theAssociation of State Drinking WaterAdministrators, and the NationalAssociation of Water Companies. Inaddition, the Agency invited the NativeAmerican Water Association toparticipate in the FACA process todevelop this rule. Although theyeventually decided not to take part, theAssociation continued to be informed ofmeetings and developments through astakeholders mailing list.

Stakeholders who participated in theFACA processes, as well as all otherinterested members of the public, wereinvited to comment on the proposedrule and NODAs. Also, as part of theAgency’s Communication Strategy, EPAsent copies of the proposed rule andNODAs to many stakeholders, includingsix tribal associations.

In addition, the Agency notifiedgovernmental entities and the private


sector of opportunities to provide inputon this Stage 1 DBPR in the FederalRegister on July 29, 1994 (59 FR38668—EPA, 1994A), November 3, 1997(62 FR 59485—EPA, 1997b), and onMarch 31, 1998 (63 FR 15974—EPA,1998a). Additionally, EPA extended thecomment period for the March 31, 1998NODA and announced a public meetingto address new information. EPAreceived approximately 213 writtencomments on the July 29, 1994 notice,approximately 57 written comments onthe November 3, 1997 notice, andapproximately 41 written comments onthe March 31, 1998 notice. Of the 213comments received concerning the 1994proposed rule, 11% were from Statesand 41% were from local governments.Also, one comment on the 1994proposal was from a tribal group thatrepresented 43 tribes. Of the 57comments received concerning the 1997Notice of Data Availability, 18% werefrom States and 37% were from localgovernments. Of the 41 commentsreceived on the 1998 Notice of DataAvailability prior to the close of thecomment period, 5% were from Statesand 15% were from local governments.

The public docket for this rulemakingcontains all comments received by theAgency and provides details about thenature of State, local, and tribalgovernment’s concerns. State and localgovernments raised several concernsincluding: the need for the Stage 1DBPR; the high costs of the rule inrelation to the uncertain benefits; thebelief that not allowing predisinfectioncredit would increase the microbial risk;and the need for flexibility inimplementing the Stage 1 DPBR andIESWTR to insure the rules areimplemented simultaneously. The onetribal comment noted that compliancewould come at a cost of diverting fundsaway from other important drinkingwater needs such as maintainingdrinking water infrastructure.

EPA understands the State, local, andtribal governments concerns with thecosts of the rule and the need to provideadditional public health protection forthe expenditure. The Agency believesthe final Stage 1 DPBR will providepublic health benefits to individuals byreducing their exposures to DBPs, whilenot requiring excessive capitalexpenditures. As discussed above, themajority of households will incuradditional costs of less than $1 permonth. As discussed in section III.E, thefinal rule maintains the existingpredisinfection credit. Finally, in the1997 DBP NODA (EPA, 1997b), EPArequested comment on four alternativeschedules for complying with the Stage1 DBPR. Most State and local

commenters preferred the option whichprovides the maximum flexibilityallowed under the SDWA for systems tocomply with the Stage 1 DBPR, and thisis the option EPA selected for the finalrule.

f. Regulatory Alternatives Considered.As required under Section 205 of theUMRA, EPA considered severalregulatory alternatives developed by theReg Neg Committee and M–DBPAdvisory Committee and suggested bystakeholders.

The Reg Neg Committee consideredseveral options including a proposedTTHMs MCL of 80 µg/L and HAA5 MCLof 60 µg/L for large systems (and asimple standard of 100 µg/l for smallsystems). Another option called for theuse of precursor removal technology toreduce the level of total organic carbonwith alternative levels ranging from 4.0to 0.5. Other options evaluated includeda 80 µg/L for TTHMs, 60 µg/L for HAA5,and 4.0 for TOC. Finally, an option wasevaluated of a 80 µg/L for TTHMs, 60µg/L for HAA5, and 5.0 for TOC. Thefinal consensus included a combinationof MCLs which would be equal for allsystem size categories and a target TOClevel. Allowing small systems to complywith a different MCL levels was rejectedbecause the rule would not adequatelyprotect the health of the populationserved by these systems. A moredetailed description of these alternativesis discussed in the document UnfundedMandates Reform Act Analysis for theStage 1 DBPR Rule which can be foundin the docket (EPA, 1998o).

Other regulatory alternatives wereconsidered by the M–DBP AdvisoryCommittee and these alternatives hadthe overall effect of reducing the cost ofthe final rule. For example, the M–DBPAdvisory Committee recommendedmaintaining the predisinfection creditafter reviewing data which suggestedthat many systems could probably meetthe proposed MCLs for DBPs whilemaintaining current disinfectionpractices. This decision was importantbecause systems would have had toincur large capital costs to remain incompliance with disinfectionrequirements if predisinfection creditswere disallowed. Thus by allowingpredisinfection, the overall cost of therule was lowered.

Also, the Committee recommendedexempting systems for the enhancedcoagulation requirements based on theirraw water quality. For example, systemswith raw-water TOC of less than orequal to 2.0 mg/L and raw-water SUVAof less than or equal to 2.0 L/mg-mwould be exempt from the enhancedcoagulation requirements. Thisexclusion was intended to promote cost-

effective enhanced coagulation (i.e.,obtaining efficiencies of TOC removalwithout excessive sludge productionand associated costs).

In conclusion, EPA believes that thealternative selected for the Stage 1 DBPRis the most cost-effective option thatachieves the objectives of the rule. Fora complete discussion of this issue seeEPA’s Regulatory Impact Analysis of theStage 1 Disinfectants/DisinfectionByproducts Rule (EPA,1998g).

3. Impacts on Small GovernmentsThe 1994 Stage 1 DBPR proposal was

done without the benefit of the UMRArequirements. However, in preparationfor the final rule, EPA conductedanalysis on small government impactsand included small government officialsor their designated representatives inthe rule making process. The FACAprocesses gave a variety of stakeholders,including small governments, theopportunity for timely and meaningfulparticipation in the regulatorydevelopment process. Representatives ofsmall government organizations were onboth the Reg. Neg. Committee and theM–DBP Advisory Committee and theirrepresentatives attended publicstakeholder meetings. Groups such asthe National Association of City andCounty Health Officials and theNational League of Cities participated inthe rulemaking process. Through suchparticipation and exchange, EPAnotified potentially affected smallgovernments of requirements underconsideration and provided officials ofaffected small governments with anopportunity to have meaningful andtimely input into the development ofregulatory proposals.

In addition, EPA will educate, inform,and advise small systems includingthose run by small government aboutDBPR requirements. One of the mostimportant components of this process isthe Small Entity Compliance Guide, asrequired by the Small BusinessRegulatory Enforcement Fairness Act of1996. This plain-English guide willexplain what actions a small entity musttake to comply with the rule. Also, theAgency is developing fact sheets thatconcisely describe various aspects andrequirements of the DBPR.

D. National Technology Transfer andAdvancement Act

Under section 12(d) of the NationalTechnology Transfer and AdvancementAct (NTTAA), the Agency is required touse voluntary consensus standards in itsregulatory activities unless to do sowould be inconsistent with applicablelaw or otherwise impractical. Voluntaryconsensus standards are technical


standards (e.g., materials specifications,test methods, sampling procedures,business practices, etc.) that aredeveloped or adopted by voluntaryconsensus standards bodies. Whereavailable and potentially applicablevoluntary consensus standards are notused by EPA, the Act requires theAgency to provide Congress, throughOMB, an explanation of the reasons fornot using such standards.

EPA’s process for selecting theanalytical test methods is consistentwith section 12(d) of the NTTAA. EPAperformed literature searches to identifyanalytical methods from industry,academia, voluntary consensusstandards bodies, and other parties thatcould be used to measure disinfectants,DBPs, and other parameters. In addition,EPA’s selection of the methodsbenefited from the recommendations ofan Advisory Committee establishedunder the FACA Act to assist theAgency with the Stage 1 DBPR. TheCommittee made available additionaltechnical experts who were well-versedin both existing analytical methods andnew developments in the field.

The results of these efforts form thebasis for the analytical methods intoday’s rule which includes: eightmethods for measuring different DBPs,of which five are EPA methods andthree are voluntary consensusstandards; nine methods for measuringdisinfectants, all of which are voluntaryconsensus standards; three voluntaryconsensus methods for measuring TOC;two EPA methods for measuringbromide; one voluntary consensusmethod for measuring UV254, and bothgovernmental and voluntary consensusmethods for measuring alkalinity.Where applicable voluntary consensusstandards were not approved, this wasdue to their inability to meet the dataquality objectives (e.g. accuracy,sensitivity, quality control procedures)necessary for demonstration ofcompliance with the relevantrequirement.

In the 1997 NODA, EPA requestedcomment on voluntary consensusstandards that had not been addressedand which should be considered foraddition to the list of approvedanalytical methods in the final rule. Noadditional consensus methods weresuggested by commenters.

E. Executive Order 12866: RegulatoryPlanning and Review

Under Executive Order 12866, (58 FR41344—EPA, 1993c) the Agency mustdetermine whether the regulatory actionis ‘‘significant’’ and therefore subject toOMB review and the requirements ofthe Executive Order. The Order defines

‘‘significant regulatory action’’ as onethat is likely to result in a rule that may:

1. Have an annual effect on theeconomy of $100 million or more oradversely affect in a material way theeconomy, a sector of the economy,productivity, competition, jobs, theenvironment, public health or safety, orState, local, or tribal governments orcommunities;

2. Create a serious inconsistency orotherwise interfere with an action takenor planned by another agency;

3. Materially alter the budgetaryimpact of entitlement, grants, user fees,or loan programs or the rights andobligations of recipients thereof; or

4. Raise novel legal or policy issuesarising out of legal mandates, thePresident’s priorities, or the principlesset forth in the Executive Order.

Pursuant to the terms of ExecutiveOrder 12866, it has been determinedthat this rule is a ‘‘significant regulatoryaction’’ because it will have an annualeffect on the economy of $100 millionor more. As such, this action wassubmitted to OMB for review. Changesmade in response to OMB suggestions orrecommendations are documented inthe public record.

F. Executive Order 12898:Environmental Justice

Executive Order 12898 establishes aFederal policy for incorporatingenvironmental justice into Federalagency missions by directing agencies toidentify and address disproportionatelyhigh and adverse human health orenvironmental effects of its programs,policies, and activities on minority andlow-income populations. The Agencyhas considered environmental justicerelated issues concerning the potentialimpacts of this action and has consultedwith minority and low-incomestakeholders.

Two aspects of today’s rule complywith the Environmental JusticeExecutive Order which requires theAgency to consider environmentaljustice issues in the rulemaking and toconsult with Environmental Justice (EJ)stakeholders. They can be classified asfollows: (1) the overall nature of therule, and (2) the convening of astakeholder meeting specifically toaddress environmental justice issues.The Stage 1 DBPR applies to communitywater systems and nontransientnoncommunity water systems that treattheir water with a chemical disinfectantfor either primary or residual treatment.Consequently, the health protectionbenefits this rule provides are equalacross all income and minority groupswithin these communities.

Finally, as part of EPA’sresponsibilities to comply with E.O.12898, the Agency held a stakeholdermeeting on March 12, 1998 to addressvarious components of pendingdrinking water regulations; and howthey may impact sensitive sub-populations, minority populations, andlow-income populations. Topicsdiscussed included treatmenttechniques, costs and benefits, dataquality, health effects, and theregulatory process. Participantsincluded national, state, tribal,municipal, and individual stakeholders.EPA conducted the meetings by videoconference call between eleven cities.This meeting was a continuation ofstakeholder meetings that started in1995 to obtain input on the Agency’sDrinking Water Programs. The majorobjectives for the March 12, 1998meeting were:

• Solicit ideas from EJ stakeholderson known issues concerning currentdrinking water regulatory efforts;

• Identify key issues of concern to EJstakeholders; and

• Receive suggestions from EJstakeholders concerning ways toincrease representation of EJcommunities in OGWDW regulatoryefforts.

In addition, EPA developed a plain-English guide specifically for thismeeting to assist stakeholders inunderstanding the multiple andsometimes complex issues surroundingdrinking water regulation.

Overall, EPA believes this rule willequally protect the health of all minorityand low-income populations served bysystems regulated under this rule fromexposure to DBPs.

G. Executive Order 13045: Protection ofChildren From Environmental HealthRisks and Safety Risks

Executive Order 13045 applies to anyrule initiated after April 21, 1997, orproposed after April 21, 1998, that (1) isdetermined to be ‘‘economicallysignificant’’ as defined under E.O. 12866and (2) concerns an environmentalhealth or safety risk that EPA has reasonto believe may have a disproportionateeffect on children. If the regulatoryaction meets both criteria, the Agencymust evaluate the environmental healthor safety effects of the planned rule onchildren, and explain why the plannedregulation is preferable to otherpotentially effective and reasonablyfeasible alternatives considered by theAgency.

The final Stage 1 DBPR is not subjectto the Executive Order because EPApublished a notice of proposedrulemaking before April 21, 1998.


However, EPA’s policy since November1, 1995, is to consistently and explicitlyconsider risks to infants and children inall risk assessments generated during itsdecision making process including thesetting of standards to protect publichealth and the environment.

EPA’s Office of Water has historicallyconsidered risks to sensitivepopulations (including fetuses, infants,and children) in establishing drinkingwater assessments, advisories or otherguidance, and standards (EPA, 1989cand EPA, 1991). The disinfection ofpublic drinking water supplies toprevent waterborne disease is the mostsuccessful public health program in U.S.history. However, numerous chemicalbyproducts (DBPs) result from thereaction of chlorine and otherdisinfectants with naturally occurringorganic and inorganic material in sourcewater, and these may have potentialhealth risks. Thus, maximizing healthprotection for sensitive subpopulationsrequires balancing risks to achieve therecognized benefits of controllingwaterborne pathogens while minimizingrisk of potential DBP toxicity. Humanexperience shows that waterbornedisease from pathogens in drinkingwater is a major concern for childrenand other subgroups (elderly, immunecompromised, pregnant women)because of their greater vulnerabilities(Gerba et al., 1996). Based on animalstudies, there is also a concern forpotential risks posed by DBPs tochildren and pregnant women (EPA,1994a; EPA, 1998a).

In developing this regulation, risks tosensitive subpopulations (includingfetuses and children) were taken intoaccount in the assessments ofdisinfectants and disinfectionbyproducts. A description of the dataavailable for evaluating risks to childrenand the conclusions drawn can be foundin the public docket for this rulemaking(EPA, 1998h). In addition, the Agencyhas evaluated alternative regulatoryoptions and selected the option that willprovide the greatest benefits for allpeople including children. See theregulatory impact analysis for acomplete discussion of the differentoptions considered. It should also benoted that the IESTWR, whichaccompanies this final rule, providesbetter controls of pathogens andachieves the goal of increasing theprotection of children.

H. Consultations With the ScienceAdvisory Board, National DrinkingWater Advisory Council, and theSecretary of Health and Human Services

In accordance with section 1412 (d)and (e) of the Act, the Agency submitted

the proposed Stage 1 DBP rule to theScience Advisory Board, NationalDrinking Water Advisory Council(NDWAC), and the Secretary of Healthand Human Services for their review.EPA has evaluated comments receivedfrom these organizations and consideredthem in developing the final Stage 1DBP rule.

I. Executive Order 12875: Enhancing theIntergovernmental Partnership

Under Executive Order 12875, EPAmay not issue a regulation that is notrequired by statute and that creates amandate upon a State, local or tribalgovernment, unless the Federalgovernment provides the fundsnecessary to pay the direct compliancecosts incurred by those governments, orEPA consults with those governments. IfEPA complies by consulting, ExecutiveOrder 12875 requires EPA to provide tothe Office of Management and Budget adescription of the extent of EPA’s priorconsultation with representatives ofaffected State, local and tribalgovernments, the nature of theirconcerns, copies of any writtencommunications from the governments,and a statement supporting the need toissue the regulation. In addition,Executive Order 12875 requires EPA todevelop an effective process permittingelected officials and otherrepresentatives of State, local and tribalgovernments ‘‘to provide meaningfuland timely input in the development ofregulatory proposals containingsignificant unfunded mandates.’’

EPA has concluded that this rule willcreate a mandate on State, local, andtribal governments and that the Federalgovernment will not provide all of thefunds necessary to pay the direct costsincurred by the State, local, and tribalgovernments in complying with themandate. In developing this rule, EPAconsulted with State and localgovernments to enable them to providemeaningful and timely input in thedevelopment of this rule. EPA alsoinvited the Native American WaterAssociation to participate in the FACAprocess to develop this rule, but theydecided not to take part in thedeliberations.

As described in Section V.C.2.e, EPAheld extensive meetings with a varietyof State and local representatives, whoprovided meaningful and timely inputin the development of the proposedrule. State and local representativeswere also part of the FACA committeesinvolved in the development of thisrule. Summaries of the meetings havebeen included in the public docket forthis rulemaking. See section V.C.2.e forsummaries of the extent of EPA’s

consultation with State, local, and tribalgovernments; the nature of thegovernment concerns; and EPA’sposition supporting the need to issuethis rule.

J. Executive Order 13084: Consultationand Coordination With Indian TribalGovernments

Under Executive Order 13084, EPAmay not issue a regulation that is notrequired by statute, that significantly oruniquely affects the communities ofIndian tribal governments, and thatimposes substantial direct compliancecosts on those communities, unless theFederal government provides the fundsnecessary to pay the direct compliancecosts incurred by the tribalgovernments, or EPA consults withthose governments. If EPA complies byconsulting, Executive Order 13084requires EPA to provide to the Office ofManagement and Budget, in a separatelyidentified section of the preamble to therule, a description of the extent of EPA’sprior consultation with representativesof affected tribal governments, asummary of the nature of their concerns,and a statement supporting the need toissue the regulation. In addition,Executive Order 13084 requires EPA todevelop an effective process permittingelected officials and otherrepresentatives of Indian tribalgovernments ‘‘to provide meaningfuland timely input in the development ofregulatory policies on matters thatsignificantly or uniquely affect theircommunities.’’

EPA has concluded that this rule willsignificantly affect communities ofIndian tribal governments. It will alsoimpose substantial direct compliancecosts on such communities, and theFederal government will not provide allthe funds necessary to pay the directcosts incurred by the tribal governmentsin complying with the rule. Indeveloping this rule, EPA consultedwith representatives of tribalgovernments pursuant to both ExecutiveOrder 12875 and Executive Order13084. EPA’s consultation, the nature ofthe governments’ concerns, and EPA’sposition supporting the need for thisrule are discussed above in thepreamble section that addressescompliance with Executive Order12875. Specifically in developing thisrule, the Agency invited the NativeAmerican Water Association toparticipate in the FACA process todevelop this rule. Although theyeventually decided not to take part, theAssociation continued to be informed ofmeetings and developments through astakeholders mailing list. As describedin Section V.C.2.e of the discussion on


UMRA, EPA held extensive meetingsthat provided the opportunity formeaningful and timely input in thedevelopment of the proposed rule.Summaries of the meetings have beenincluded in the public docket for thisrulemaking.

K. Submission to Congress and theGeneral Accounting Office

The Congressional Review Act, 5U.S.C. 801 et seq., as added by the SmallBusiness Regulatory EnforcementFairness Act of 1996, generally providesthat before a rule may take effect, theagency promulgating the rule mustsubmit a rule report, which includes acopy of the rule, to each House of theCongress and to the Comptroller Generalof the United States. EPA will submit areport containing this rule and otherrequired information to the U.S. Senate,the U.S. House of Representatives, andthe Comptroller General of the UnitedStates prior to publication of the rule inthe Federal Register. A major rulecannot take effect until 60 days after itis published in the Federal Register.This rule is a ‘‘major rule’’ as defined by5 U.S.C. 804(2). This rule will beeffective February 16, 1999.

L. Likely Effect of Compliance With theStage 1 DBPR on the Technical,Financial, and Managerial Capacity ofPublic Water Systems

Section 1420(d)(3) of the SDWA asamended requires that, in promulgatinga NPDWR, the Administrator shallinclude an analysis of the likely effectof compliance with the regulation onthe technical, financial, and managerialcapacity of public water systems. Thefollowing analysis has been performedto fulfill this statutory obligation.

Overall water system capacity isdefined in EPA guidance (EPA 816–R–98–006) as the ability to plan for,achieve, and maintain compliance withapplicable drinking water standards.Capacity has three components:technical, managerial, and financial.

Technical capacity is the physical andoperational ability of a water system tomeet SDWA requirements. Technicalcapacity refers to the physicalinfrastructure of the water system,including the adequacy of source waterand the adequacy of treatment, storage,and distribution infrastructure. It alsorefers to the ability of system personnelto adequately operate and maintain thesystem and to otherwise implementrequisite technical knowledge. A watersystem’s technical capacity can bedetermined by examining key issuesand questions, including:

• Source water adequacy. Does thesystem have a reliable source of

drinking water? Is the source ofgenerally good quality and adequatelyprotected?

• Infrastructure adequacy. Can thesystem provide water that meets SDWAstandards? What is the condition of itsinfrastructure, including well(s) orsource water intakes, treatment, storage,and distribution? What is theinfrastructure’s life expectancy? Doesthe system have a capital improvementplan?

• Technical knowledge andimplementation. Is the system’s operatorcertified? Does the operator havesufficient technical knowledge ofapplicable standards? Can the operatoreffectively implement this technicalknowledge? Does the operatorunderstand the system’s technical andoperational characteristics? Does thesystem have an effective operation andmaintenance program?

Managerial capacity is the ability of awater system to conduct its affairs in amanner enabling the system to achieveand maintain compliance with SDWArequirements. Managerial capacity refersto the system’s institutional andadministrative capabilities.

Managerial capacity can be assessedthrough key issues and questions,including:

• Ownership accountability. Are thesystem owner(s) clearly identified? Canthey be held accountable for the system?

• Staffing and organization. Are thesystem operator(s) and manager(s)clearly identified? Is the systemproperly organized and staffed? Dopersonnel understand the managementaspects of regulatory requirements andsystem operations? Do they haveadequate expertise to manage watersystem operations? Do personnel havethe necessary licenses andcertifications?

• Effective external linkages. Does thesystem interact well with customers,regulators, and other entities? Is thesystem aware of available externalresources, such as technical andfinancial assistance?

Financial capacity is a water system’sability to acquire and manage sufficientfinancial resources to allow the systemto achieve and maintain compliancewith SDWA requirements.

Financial capacity can be assessedthrough key issues and questions,including:

• Revenue sufficiency. Do revenuescover costs? Are water rates and chargesadequate to cover the cost of water?

• Credit worthiness. Is the systemfinancially healthy? Does it have accessto capital through public or privatesources?

• Fiscal management and controls.Are adequate books and recordsmaintained? Are appropriate budgeting,accounting, and financial planningmethods used? Does the system manageits revenues effectively?

There are 76,051 systems affected bythis rule. Of these, 12,998 will have tomodify their treatment process andundertake disinfectant and DBPmonitoring and reporting. Some of thissmaller group may also be required todo DBP precursor monitoring andreporting. The other 63,063 systems willneed to do disinfectant and DBPmonitoring and reporting, but will notneed to modify their treatment process.Some of this larger group may also berequired to do DBP precursormonitoring and reporting.

Systems not modifying treatment arenot generally expected to requiresignificantly increased technical,financial, or managerial capacity tocomply with these new requirements.Certainly some individual facilities mayhave weaknesses in one or more of theseareas but overall, systems should haveor be able to obtain the capacity neededfor these activities.

Systems needing to modify treatmentwill employ one or more of a variety ofsteps. The steps expected to beemployed by 50% or more of subpart Hsystems and by eight percent or more ofground water systems covered by therule include a combination of low costalternatives, including switching tochloramines for residual disinfection,moving the point of disinfectantapplication, and improving precursorremoval. EPA estimates that less thanseven percent of systems in any categorywill resort to higher cost alternatives,such as switching to ozone orchloramines for primary disinfection orusing GAC or membranes for precursorremoval. These higher cost alternativesmay also provide other treatmentbenefits, so the cost may be somewhatoffset by eliminating the need fortechnologies to remove othercontaminants. Some of these systemsmay choose nontreatment alternativessuch as consolidation with anothersystem or changing to a higher qualitywater source.

Furthermore, there are a number ofactions that are expected to be takendisproportionately by smaller sizedsystems (that is to say, a greaterpercentage of smaller sized systems willundertake than will larger sizedsystems). These steps include increasedplant staffing and additional stafftraining to understand process controlstrategy. Small systems will be requiredto do this since larger systems havealready undertaken these changes to


some extent for compliance with the1979 TTHM rule.

For many systems serving less than10,000 persons which need to maketreatment modifications, anenhancement of technical, financial,and managerial capacity may likely beneeded. As the preceding paragraphmakes clear, these systems will bemaking structural improvements andenhancing laboratory and staff capacity.Larger sized systems have typicallyalready made these improvements aspart of normal operations. Meeting therequirements of the Stage 1 DBPR willrequire operating at a higher level ofsophistication and in a better state ofrepair than some plants serving lessthan 10,000 people have consideredacceptable in the past.

Certainly there will be exceptions insystems serving both below 10,000persons and above. Some larger plantswill doubtless find their technical,managerial, and financial capacity taxedby the new requirements. Likewise,some plants serving less than 10,000persons will already have more thanadequate technical, financial, andmanagerial capacity to meet theserequirements. However, in general, thesystems serving less than 10,000persons needing to make treatmentmodifications will be the ones mostneeding to enhance their capacity.

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43. Orme, J. D.H. Taylor, R.D. Laurie, and R.J.Bull. 1985. Effects of Chlorine Dioxideon Thyroid Function in Neonatal Rats. J.Tox. and Environ. Health. 15:315–322.

44. OSTP. 1985. Chemical Carcinogens; AReview of the Science and Its AssociatedPrinciples, February 1985. Presented inRisk Analysis: A guide to Principles andMethods for Analyzing Health andEnvironmental Risks. Appendix G.Federal Register, March 14, 1985. Pages10371–10442.

45. Owen, D. M.; Amy, G. L. and Z. K.Chowdhury. 1993. Characterization ofNatural Organic Matter and ItsRelationship to Treatability. AWWAResearch Foundation & AWWA, Denver,CO.

46. Poole, C. 1997. Analytical Meta-Analysisof Epidemiological Studies ofChlorinated Drinking Water and Cancer:Quantitative Review and Reanalysis ofthe Work Published by Morris et al., AmJ Public Health 1992:82:955–963.National Center for EnvironmentalAssessment, Office of Research andDevelopment, September 30, 1997.

47. Randtke, S. J.; Hoehn, R. C.; Knocke, W.R.; Dietrich, A. M.; Long, B. W.; and N.A. Wang. 1994. ComprehensiveAssessment of DBP Precursor Removalby Enhanced Coagulation and Softening.Proc. AWWA Ann. Conf. (WaterQuality), New York, NY, pp. 737–777.

48. Reif, J. S. et al. 1996. Reproductive andDevelopmental Effects of DisinfectionBy-products in Drinking Water.Environmental Health Prospectives.104(10):1056–1061.

49. Sanders, V.M., B.M. Kauffman, K.L.White, K.A. Douglas, D.W. Barnes, L.E.Sain, T.J. Bradshaw, J.F. Borzelleca andA.E. Munson. 1982. Toxicology ofchloral hydrate in the mouse. Environ.Health Perspect. 44:137–146.

50. Savitz, D. A., Andrews, K. W. and L. M.Pastore. 1995. Drinking Water andPregnancy Outcome in Central NorthCarolina: Source, Amount, andTrihalomethane levels. Environ. HealthPerspectives. 103(6), 592–596.

51. Shorney, H. L., Randtke, S. J., Hargette,P. H., Mann, P. D., Hoehn, R.C., Knocke,W. R., Dietrich, A. M. and B. W. Long.1996. The Influence of Raw WaterQuality on Enhanced Coagulation andSoftening for the Removal of NOM andDBP Formation Potential, Proceedings1996 AWWA Annual Conference,Toronto, Ontario, Canada.

52. Singer, P. C., Harrington, G. W.,Thompson, J. D. and M. C. White. 1995.Enhanced Coagulation and EnhancedSoftening for the Removal of DisinfectionBy-Product Precursors: An Evaluation.Report prepared for the AWWAGovernment Affairs Office, Washington,DC, by the Dept. of EnvironmentalSciences and Engineering, UNC, ChapelHill, NC.

53. Singer, P. C., Harrington, G. W.,Thompson, J. and M. White. 1996.Enhanced Coagulation and EnhancedSoftening for the Removal of DisinfectionBy-Product Precursors: An Evaluation,Report to AWWA Disinfectants/Disinfection By-Products TechnicalAdvisory Workgroup of the Water UtilityCouncil, December 1996.

54. Smith, M.K., Randall, J.L., Read, E.J., andStober, J.A. 1989. Teratogenic activity oftrichloroacetic acid in the rat. Teratology40:445–451.

55. Summers, R.S., G. Solarik, V.A. Hatcher,R.S. Isabel, and J.F. Stile. 1997.Analyzing the Impacts of PredisinfectionThrough Jar Testing, Proceedings,AWWA Water Quality TechnologyConference, Denver, CO.

56. Tseng, T. and M. Edwards. 1997.Considerations in OptimizingCoagulation. Proc. 1996 AWWA WaterQual. Technol. Conf., Boston, Mass.

57. U.S. EPA. 1979. National Interim PrimaryDrinking Water Regulations; Control ofTrihalomethanes in Drinking Water. Fed.Reg., 44:231:68624. (November 29, 1979)

58. U.S. EPA. 1983. EPA Method 310.1.Methods of Chemical Analysis of Waterand Wastes. Envir. Monitoring SystemsLaboratory, Cincinnati, OH. EPA 600/4–79–020. 460 pp.

59. U.S. EPA. 1986. Guidelines forCarcinogen Risk Assessment, Fed. Reg.51(185):33992–34003. EPA/600/8–87/045. NTIS PB88–123997.

60. U.S. EPA. 1987. Drinking WaterRegulations; Public Notification; FinalRule. Federal Register. Vol. 52, No. 208,Wednesday, Oct. 28, 1987—Part II. pp.41534–41550.

61. U.S. EPA. 1988. EPA Method 502.2.Methods for the Determination ofOrganic Compounds in Drinking Water.EPA 600/4–88–039. PB91–231480.Revised July 1991.

62. U.S. EPA. 1989a. National PrimaryDrinking Water Regulations; Filtration,Disinfection; Turbidity, Giardia lamblia,Viruses, Legionella, and HeterotrophicBacteria; Final Rule. Part II. Fed. Reg.,54:124:27486. (June 29, 1989)

63. U.S. EPA 1989b. National PrimaryDrinking Water Regulations; TotalColiforms (Including Fecal Coliform andE. Coli); Final Rule. Fed. Reg.,54:124:27544. (June 29, 1989)

64. U.S. EPA. 1989c. Review ofEnvironmental Contaminants andToxicology. USEPA. Office of DrinkingWater Health Advisories, Volume 106.225pp.

65. U.S. EPA. 1990. EPA Methods 551, 552.Methods for the Determination ofOrganic Compounds in Drinking Water—Supplement I. EPA 600/4–90–020.PB91–146027.

66 U.S. EPA. 1991. National PrimaryDrinking Water Regulations: Final Rule.Fed, reg., 56:20, January 30, 1991 3526–3597.

67. U.S. EPA. 1992. EPA Methods 524.2,552.1. Methods for the Determination ofOrganic Compounds in Drinking Water—Supplement II. EPA 600/R–92/129.PB92–207703.

68. U.S. EPA. 1993a. Draft Drinking WaterHealth Criteria Document for Bromate.Office of Science and Technology, Officeof Water. Sep. 30, 1993.

69. U.S. EPA. 1993b. EPA Method 300.0. TheDetermination of Inorganic Anions byIon Chromatography in the Manual‘‘Methods for the Determination ofInorganic Substances in EnvironmentalSamples,’’ EPA/600/R/93/100. NTIS,PB94120821.

70. U.S. EPA. 1993c. Executive Order 12866:Regulatory Planning and Review.Federal Register. Vol. 58, No. 190.October 4, 1993. 51735–51744.

71. U.S. EPA/ILSI. 1993. A Review ofEvidence on Reproductive andDevelopmental Effects of DisinfectionBy-Products in Drinking Water.Washington: U.S. EnvironmentalProtection Agency and International LifeSciences Institute.


72. U.S. EPA. 1994a. National PrimaryDrinking Water Regulations;Disinfectants and DisinfectionByproducts; Proposed Rule. Fed. Reg.,59:145:38668. (July 29, 1994).

73. U.S. EPA. 1994b. National PrimaryDrinking Water Regulations; EnhancedSurface Water Treatment Requirements;Proposed Rule. Fed. Reg., 59:145:38832.(July 29, 1994).

74. U.S. EPA. 1994c. National PrimaryDrinking Water Regulations; MonitoringRequirements for Public Drinking WaterSupplies; Proposed Rule. Fed. Reg.,59:28:6332. (February 10, 1994).

75. U.S. EPA. 1994d. Final Draft DrinkingWater Health Criteria Document forChlorine Dioxide, Chlorite and Chlorate.Office of Science and Technology, Officeof Water. March 31, 1994.

76. U.S. EPA. 1994e. Draft Drinking WaterHealth Criteria Document for Chlorine,Hypochlorous Acid and HypochloriteIon. Office of Science and Technology,Office of Water.

77. U.S. EPA. 1994f. Health and EcologicalCriteria Div., OST. Final Draft for theDrinking Water Criteria Document onTrihalomethanes. Apr. 8. 1994.

78. U.S. EPA. 1994g. Draft Drinking WaterHealth Criteria Document forChlorinated Acetic Acids/Alcohols/Aldehydes and Ketones. Office ofScience and Technology, Office of Water.

79. U.S. EPA. 1994h. Draft Drinking WaterHealth Criteria Document forChloramines. Office of Science andTechnology, Office of Water.

80. U.S. Environmental Protection Agency.1994i. Regulatory Impact Analysis ofProposed Disinfectant/DisinfectionByproduct Regulations. Washington, DC.EPA–68–C3–0368.

81. U.S. EPA. 1995. Methods for theDetermination of Organic Compounds inDrinking Water. Supplement III. EPA–600/R–95/131. NTIS, PB95261616.

82. U.S. EPA. 1996a. National PrimaryDrinking Water Regulations: MonitoringRequirements for Public Drinking WaterSupplies; Final Rule. Fed. Reg.,61:94:24354. (May 14, 1996)

83. U.S. EPA. 1996b. Proposed Guidelines forCarcinogen Risk Assessment. U.S. EPA,April 23, 1996.

84. U.S. EPA. 1997a. National PrimaryDrinking Water Regulations; InterimEnhanced Surface Water Treatment Rule;Notice of Data Availability; ProposedRule. Fed. Reg., 62 (No. 212): 59486–59557. (November 3, 1997).

85. U.S. EPA. 1997b. National PrimaryDrinking Water Regulations;Disinfectants and DisinfectionByproducts; Notice of Data Availability;Proposed Rule. Fed. Reg., 62 (No. 212):59388–59484. (November 3, 1997).

86. U.S. EPA. 1997c. Summaries of NewHealth Effects Data. Office of Scienceand Technology, Office of Water.October 1997.

87. U.S. EPA. 1997d. External Peer Review ofCMA Study –2– Generation, EPAContract No. 68–C7–0002, WorkAssignment B–14, The Cadmus Group,Inc., October 9, 1997.

88. U.S. EPA. 1997e. Method 300.1.Determination of Inorganic Anions inDrinking Water by Ion Chromatography.Revision 1.0. USEPA National ExposureResearch Laboratory, Cincinnati OH.

89. U.S. EPA. 1997f. Performance BasedMeasurement System. Notice of Intent.Federal Register, October 6, 1997. Vol.62, No. 193., 52098–52100.

90. U.S. EPA. 1997g. Manual for theCertification of Laboratories AnalyzingDrinking Water, Fourth Edition, Office ofWater Resource Center (RC–4100), EPA815–B–97–001. March 1997.

91. U.S. EPA. 1998a. National PrimaryDrinking Water Regulations;Disinfectants and DisinfectionByproducts; Notice of Data Availability;Proposed Rule. Fed. Reg., 63 (No. 61):15606–15692. (March 31, 1998).

92. U.S. EPA. 1998b. Dichloroacetic acid:Carcinogenicity IdentificationCharacterization Summary. NationalCenter for Environmental Assessment—Washington Office. Office of Researchand Development. March 1998. EPA815–B–98–010. PB 99–111387.

93. U.S. EPA. 1998c. Quantification ofBladder Cancer Risk from Exposure toChlorinated Surface Water. Office ofScience and Technology, Office of Water.November 9, 1998.

94. U.S. EPA. 1998d. Health RiskAssessment/Characterization of theDrinking Water Disinfection ByproductChlorine Dioxide and the DegradationByproduct Chlorite. Office of Scienceand Technology, Office of Water.October 15, 1998. EPA 815–B–98–008.PB 99–111361.

95. U.S. EPA. 1998e. Health RiskAssessment/Characterization of theDrinking Water Disinfection ByproductBromate. Office of Science andTechnology, Office of Water. September30, 1998. EPA 815–B–98–007. PB 99–111353.

96. U.S. EPA. 1998f. Panel Report andRecommendation for ConductingEpidemiological Research on PossibleReproductive and Developmental Effectsof Exposure to Disinfected DrinkingWater. Office of Research andDevelopment. February 12, 1998.

97. U.S. EPA. 1998g. Regulatory ImpactAnalysis of Final Disinfectant/Disinfection By-Products Regulations.Washington, D.C. EPA Number 815–B–98–002. PB 99–111304.

98. U.S. EPA. 1998h. Health Risks to Fetuses,Infants, and Children (final Stage 1 DBPRule). Office of Science and Technology.Office of Water. November 19, 1998. EPA815–B–98–009. PB 99–111379.

99. U.S. EPA. 1998i. Revisions to StatePrimacy Requirements To ImplementSafe Drinking Water Act Amendments:Final Rule. Federal Register, Tuesday,April 28, 1998, Vol. 63, No.81, 23362–23368.

100. U.S. EPA. 1998j. Revision of ExistingVariance and Exemption Regulations toComply with Requirements of the SafeDrinking Water Act; Final Rule. FederalRegister, Vol 63, No. 157. Friday, Aug.14, 1998. pp. 43833–43851.

101. U.S. EPA. 1998k. Cost and TechnologyDocument for Controlling Disinfectantsand Disinfection Byproducts. Office ofGround Water and Drinking Water.Washington, DC. EPA 815–R–98–014. PB99–111486.

102. U.S. EPA. 1998l. Synthesis of the Peer-Review of Meta-analysis ofEpidemiologic Data on Risks of Cancerfrom Chlorinated Drinking Water.National Center for EnvironmentalAssessment, Office of Research andDevelopment, February 16, 1998.

103. U.S. EPA. 1998m. NCEA Position PaperRegarding Risk Assessment Use of theResults from the Published Study: Morriset al. Am J Public Health 1992;82:955–963. National Center for EnvironmentalAssessment, Office of Research andDevelopment, October 7, 1997.

104. U.S. EPA. 1998n. A Suggested Approachfor Using the Current EpidemiologicLiterature to Estimate the PossibleCancer Risk from Water Chlorination, forthe Purposes of the Regulatory ImpactAnalysis. ORD, National Center forEnvironmental Assessment. August 27,1998.

105. U.S. EPA. 1998o. Unfunded MandatesReform Act Analysis for the Stage 1Disinfectant and Disinfection ByproductRule. Office of Groundwater andDrinking Water.

106. U.S. EPA. 1998p. Health RiskAssessment/Characterization of theDrinking Water Disinfection ByproductChloroform. Office of Science andTechnology, Office of Water. November4, 1998. EPA 815–B–98–006. PB 99–111346.

107. U.S. EPA. 1998q. Small SystemCompliance Technology List for theStage 1 DBP Rule. Office of Groundwaterand Drinking Water. EPA 815–R–98–017.PB 99–111510.

108. U.S. EPA. 1998r. Technologies and Costsfor Point-of-Entry (POE) and Point-of-Use(POU) Devices for Control of DisinfectionByproducts. Office of Groundwater andDrinking Water. EPA 815–R–98–016. PB99–111502.

109. U.S. EPA. 1998s. National-LevelAffordability Criteria Under the 1996Amendments to the Safe Drinking WaterAct. Office of Groundwater and DrinkingWater. August 19, 1998.

110. U.S. EPA. 1998t. Variance TechnologyFindings for Contaminants RegulatedBefore 1996. Office of Water. September1998. EPA 815–R–98–003.

111. U.S. EPA. 1998u. OccurrenceAssessment for Disinfectants andDisinfection Byproducts in PublicDrinking Water Supplies. Office ofGroundwater and Drinking Water. EPA815–B–98–004. November 13, 1998. PB99–111320.

112. USGS. 1989. Method I–1030–85.Techniques of Water ResourcesInvestigations of the U.S. GeologicalSurvey. Book 5, Chapter A–1, 3rd ed.,U.S. Government Printing Office.

113. Waller K., Swan S. H., DeLorenze G.,Hopkins B., 1998. Trihalomethanes indrinking water and spontaneousabortion. Epidemiology. 9(2):134–140.


114. White, M. C., Thompson, D., Harrington,G. W., and P.S. Singer. 1997. EvaluatingCriteria for Enhanced CoagulationCompliance. AWWA, 89:5:64.

115. Xie, Yuefeng. 1995. Effects of SodiumChloride on DBP Analytical Results,Extended Abstract, Division ofEnvironmental Chemistry, AmericanChemical Society Annual Conference,Chicago, IL, Aug. 21–26, 1995.

List of Subjects

40 CFR Part 9

Environmental protection, Reportingand recordkeeping requirements.

40 CFR Parts 141 and 142

Analytical methods, Drinking water,Environmental protection, Incorporationby reference, Intergovernmentalrelations, Public utilities, Reporting andrecordkeeping requirements, Utilities,Water supply.

Dated: November 30, 1998.Carol M. Browner,Administrator.

For the reasons set out in thepreamble, title 40, chapter I of the Codeof Federal Regulations is amended asfollows:

PART 9—[AMENDED]

1. The authority citation for part 9continues to read as follows:

Authority: 7 U.S.C. 135 et seq., 136–136y;15 U.S.C. 2001, 2003, 2005, 2006, 2601–2671;21 U.S.C. 331j, 346a, 348; 31 U.S.C. 9701; 33U.S.C. 1251 et seq., 1311, 1313d, 1314, 1318,1321, 1326, 1330, 1342, 1344, 1345 (d) and(e), 1361; E.O. 11735, 38 FR 21243, 3 CFR,1971–1975 Comp. p. 973; 42 U.S.C. 241,242b, 243, 246, 300f, 300g, 300g–1, 300g–2,300g–3, 300g–4, 300g–5, 300g–6, 300j–1,300j–2, 300j–3, 300j–4, 300j–9, 1857 et seq.,6901–6992k, 7401–7671q, 7542, 9601–9657,11023, 11048.

2. In § 9.1 the table is amended byadding under the indicated heading: thenew entries in numerical order to readas follows:

§ 9.1 OMB approvals under the PaperworkReduction Act.

* * * * *

40 CFR citation OMB con-trol No.

* * * * *National Primary Drinking

Water Regulations

* * * * *141.130–141.132 ...................... 2040–0204141.134–141.135 ...................... 2040–0204

* * * * *

PART 141—NATIONAL PRIMARYDRINKING WATER REGULATIONS


Authority: 42 U.S.C. 300f, 300g–1, 300g–2,300g–3, 300g–4, 300g–5, 300g–6, 300j–4,300j–9, and 300j–11.

4. Section 141.2 is amended byadding the following definitions inalphabetical order to read as follows:

§ 141.2 Definitions.

* * * * *Enhanced coagulation means the

addition of sufficient coagulant forimproved removal of disinfectionbyproduct precursors by conventionalfiltration treatment.* * * * *

Enhanced softening means theimproved removal of disinfectionbyproduct precursors by precipitativesoftening.* * * * *

GAC10 means granular activatedcarbon filter beds with an empty-bedcontact time of 10 minutes based onaverage daily flow and a carbonreactivation frequency of every 180days.* * * * *

Haloacetic acids (five) (HAA5) meanthe sum of the concentrations inmilligrams per liter of the haloaceticacid compounds (monochloroaceticacid, dichloroacetic acid, trichloroaceticacid, monobromoacetic acid, anddibromoacetic acid), rounded to twosignificant figures after addition.* * * * *

Maximum residual disinfectant level(MRDL) means a level of a disinfectantadded for water treatment that may notbe exceeded at the consumer’s tapwithout an unacceptable possibility ofadverse health effects. For chlorine andchloramines, a PWS is in compliancewith the MRDL when the runningannual average of monthly averages ofsamples taken in the distributionsystem, computed quarterly, is less thanor equal to the MRDL. For chlorinedioxide, a PWS is in compliance withthe MRDL when daily samples are takenat the entrance to the distributionsystem and no two consecutive dailysamples exceed the MRDL. MRDLs areenforceable in the same manner asmaximum contaminant levels underSection 1412 of the Safe Drinking WaterAct. There is convincing evidence thataddition of a disinfectant is necessaryfor control of waterborne microbialcontaminants. Notwithstanding theMRDLs listed in § 141.65, operators mayincrease residual disinfectant levels ofchlorine or chloramines (but not

chlorine dioxide) in the distributionsystem to a level and for a timenecessary to protect public health toaddress specific microbiologicalcontamination problems caused bycircumstances such as distribution linebreaks, storm runoff events, sourcewater contamination, or cross-connections.* * * * *

Maximum residual disinfectant levelgoal (MRDLG) means the maximumlevel of a disinfectant added for watertreatment at which no known oranticipated adverse effect on the healthof persons would occur, and whichallows an adequate margin of safety.MRDLGs are nonenforceable healthgoals and do not reflect the benefit ofthe addition of the chemical for controlof waterborne microbial contaminants.* * * * *

Subpart H systems means publicwater systems using surface water orground water under the direct influenceof surface water as a source that aresubject to the requirements of subpart Hof this part.* * * * *

SUVA means Specific UltravioletAbsorption at 254 nanometers (nm), anindicator of the humic content of water.It is a calculated parameter obtained bydividing a sample’s ultravioletabsorption at a wavelength of 254 nm(UV 254) (in m =1) by its concentration ofdissolved organic carbon (DOC) (in mg/L).* * * * *

Total Organic Carbon (TOC) meanstotal organic carbon in mg/L measuredusing heat, oxygen, ultravioletirradiation, chemical oxidants, orcombinations of these oxidants thatconvert organic carbon to carbondioxide, rounded to two significantfigures.* * * * *

5. Section 141.12 is revised to read asfollows:

§ 141.12 Maximum contaminant levels fortotal trihalomethanes.

The maximum contaminant level of0.10 mg/L for total trihalomethanes (thesum of the concentrations ofbromodichloromethane,dibromochloromethane,tribromomethane (bromoform), andtrichloromethane (chloroform)) appliesto subpart H community water systemswhich serve a population of 10,000people or more until December 16,2001. This level applies to communitywater systems that use only groundwater not under the direct influence ofsurface water and serve a population of10,000 people or more until December


16, 2003. Compliance with themaximum contaminant level for totaltrihalomethanes is calculated pursuantto § 141.30. After December 16, 2003,this section is no longer applicable.

6. Section 141.30 is amended byrevising the the first sentences inparagraphs (d) and (f) and addingparagraph (h) to read as follows:

§ 141.30 Total trihalomethanes sampling,analytical and other requirements.

* * * * *(d) Compliance with § 141.12 shall be

determined based on a running annualaverage of quarterly samples collectedby the system as prescribed inparagraph (b)(1) or (2) of thissection. * * ** * * * *

(f) Before a community water systemmakes any significant modifications toits existing treatment process for thepurposes of achieving compliance with§ 141.12, such system must submit andobtain State approval of a detailed plansetting forth its proposed modificationand those safeguards that it willimplement to ensure that thebacteriological quality of the drinkingwater served by such system will not beadversely affected by suchmodification. * * ** * * * *

(h) The requirements in paragraphs (a)through (g) of this section apply tosubpart H community water systemswhich serve a population of 10,000 ormore until December 16, 2001. Therequirements in paragraphs (a) through(g) of this section apply to communitywater systems which use only groundwater not under the direct influence ofsurface water that add a disinfectant(oxidant) in any part of the treatmentprocess and serve a population of10,000 or more until December 16, 2003.After December 16, 2003, this section isno longer applicable.

7. Section 141.32 is amended byrevising the heading in paragraph (a)introductory text, the first sentence ofparagraph (a)(1)(iii) introductory text,and the first sentence of paragraph (c),and adding paragraphs (a)(1)(iii)(E) and(e) (76) through (81), to read as follows:

§ 141.32 Public notification.* * * * *

(a) Maximum contaminant levels(MCLs), maximum residual disinfectantlevels (MRDLs). * * *

(1) * * *(iii) For violations of the MCLs of

contaminants or MRDLs of disinfectantsthat may pose an acute risk to humanhealth, by furnishing a copy of thenotice to the radio and televisionstations serving the area served by the

public water system as soon as possiblebut in no case later than 72 hours afterthe violation. **** * * * *

(E) Violation of the MRDL for chlorinedioxide as defined in § 141.65 anddetermined according to § 141.133(c)(2).* * * * *

(c) * * * The owner or operator of acommunity water system must give acopy of the most recent public notice forany outstanding violation of anymaximum contaminant level, or anymaximum residual disinfectant level, orany treatment technique requirement, orany variance or exemption schedule toall new billing units or new hookupsprior to or at the time service begins.* * * * *

(e) * * *(76) Chlorine. The United States

Environmental Protection Agency (EPA)sets drinking water standards and hasdetermined that chlorine is a healthconcern at certain levels of exposure.Chlorine is added to drinking water asa disinfectant to kill bacteria and otherdisease-causing microorganisms and isalso added to provide continuousdisinfection throughout the distributionsystem. Disinfection is required forsurface water systems. However, at highdoses for extended periods of time,chlorine has been shown to affect bloodand the liver in laboratory animals. EPAhas set a drinking water standard forchlorine to protect against the risk ofthese adverse effects. Drinking waterwhich meets this EPA standard isassociated with little to none of this riskand should be considered safe withrespect to chlorine.

(77) Chloramines. The United StatesEnvironmental Protection Agency (EPA)sets drinking water standards and hasdetermined that chloramines are ahealth concern at certain levels ofexposure. Chloramines are added todrinking water as a disinfectant to killbacteria and other disease-causingmicroorganisms and are also added toprovide continuous disinfectionthroughout the distribution system.Disinfection is required for surfacewater systems. However, at high dosesfor extended periods of time,chloramines have been shown to affectblood and the liver in laboratoryanimals. EPA has set a drinking waterstandard for chloramines to protectagainst the risk of these adverse effects.Drinking water which meets this EPAstandard is associated with little to noneof this risk and should be consideredsafe with respect to chloramines.

(78) Chlorine dioxide. The UnitedStates Environmental Protection Agency(EPA) sets drinking water standards and

has determined that chlorine dioxide isa health concern at certain levels ofexposure. Chlorine dioxide is used inwater treatment to kill bacteria andother disease-causing microorganismsand can be used to control tastes andodors. Disinfection is required forsurface water systems. However, at highdoses, chlorine dioxide-treated drinkingwater has been shown to affect blood inlaboratory animals. Also, high levels ofchlorine dioxide given to laboratoryanimals in drinking water have beenshown to cause neurological effects onthe developing nervous system. Theseneurodevelopmental effects may occuras a result of a short-term excessivechlorine dioxide exposure. To protectagainst such potentially harmfulexposures, EPA requires chlorinedioxide monitoring at the treatmentplant, where disinfection occurs, and atrepresentative points in the distributionsystem serving water users. EPA has seta drinking water standard for chlorinedioxide to protect against the risk ofthese adverse effects.

Note: In addition to the language in thisintroductory text of paragraph (e)(78),systems must include either the language inparagraph (e)(78)(i) or (e)(78)(ii) of thissection. Systems with a violation at thetreatment plant, but not in the distributionsystem, are required to use the language inparagraph (e)(78)(i) of this section and treatthe violation as a nonacute violation.Systems with a violation in the distributionsystem are required to use the language inparagraph (e)(78)(ii) of this section and treatthe violation as an acute violation.

(i) The chlorine dioxide violationsreported today are the result ofexceedances at the treatment facilityonly, and do not include violationswithin the distribution system servingusers of this water supply. Continuedcompliance with chlorine dioxide levelswithin the distribution systemminimizes the potential risk of theseviolations to present consumers.

(ii) The chlorine dioxide violationsreported today include exceedances ofthe EPA standard within thedistribution system serving water users.Violations of the chlorine dioxidestandard within the distribution systemmay harm human health based on short-term exposures. Certain groups,including pregnant women, infants, andyoung children, may be especiallysusceptible to adverse effects ofexcessive exposure to chlorine dioxide-treated water. The purpose of this noticeis to advise that such persons shouldconsider reducing their risk of adverseeffects from these chlorine dioxideviolations by seeking alternate sourcesof water for human consumption untilsuch exceedances are rectified. Local


and State health authorities are the bestsources for information concerningalternate drinking water.

(79) Disinfection byproducts andtreatment technique for DBPs. TheUnited States Environmental ProtectionAgency (EPA) sets drinking waterstandards and requires the disinfectionof drinking water. However, when usedin the treatment of drinking water,disinfectants react with naturally-occurring organic and inorganic matterpresent in water to form chemicalscalled disinfection byproducts (DBPs).EPA has determined that a number ofDBPs are a health concern at certainlevels of exposure. Certain DBPs,including some trihalomethanes (THMs)and some haloacetic acids (HAAs), havebeen shown to cause cancer inlaboratory animals. Other DBPs havebeen shown to affect the liver and thenervous system, and cause reproductiveor developmental effects in laboratoryanimals. Exposure to certain DBPs mayproduce similar effects in people. EPAhas set standards to limit exposure toTHMs, HAAs, and other DBPs.

(80) Bromate. The United StatesEnvironmental Protection Agency (EPA)sets drinking water standards and hasdetermined that bromate is a healthconcern at certain levels of exposure.Bromate is formed as a byproduct ofozone disinfection of drinking water.Ozone reacts with naturally occurringbromide in the water to form bromate.Bromate has been shown to producecancer in rats. EPA has set a drinkingwater standard to limit exposure tobromate.

(81) Chlorite. The United StatesEnvironmental Protection Agency (EPA)sets drinking water standards and hasdetermined that chlorite is a healthconcern at certain levels of exposure.Chlorite is formed from the breakdownof chlorine dioxide, a drinking waterdisinfectant. Chlorite in drinking waterhas been shown to affect blood and thedeveloping nervous system. EPA has seta drinking water standard for chlorite toprotect against these effects. Drinkingwater which meets this standard isassociated with little to none of theserisks and should be considered safewith respect to chlorite.* * * * *

8. Subpart F is amended by revisingthe subpart heading and adding§§ 141.53 and 141.54 to read as follows:

Subpart F—Maximum ContaminantLevel Goals and Maximum ResidualDisinfectant Level Goals

* * * * *

§ 141.53—Maximum contaminant level goalsfor disinfection byproducts.

MCLGs for the following disinfectionbyproducts are as indicated:

Disinfection byproduct MCLG(mg/L)

Chloroform ...................................... ZeroBromodichloromethane ................... ZeroBromoform ...................................... ZeroBromate .......................................... ZeroDichloroacetic acid .......................... ZeroTrichloroacetic acid ......................... 0.3Chlorite ............................................ 0.8Dibromochloromethane ................... 0.06

§ 141.54 Maximum residual disinfectantlevel goals for disinfectants.

MRDLGs for disinfectants are asfollows:

Disinfectant residual MRDLG(mg/L)

Chlorine ............................... 4 (as Cl 2).Chloramines ......................... 4 (as Cl 2).Chlorine dioxide ................... 0.8 (as ClO2)

9. Subpart G is amended by revisingthe subpart heading and adding§§ 141.64 and 141.65 to read as follows:

Subpart G—National Revised PrimaryDrinking Water Regulations: MaximumContaminant Levels and MaximumResidual Disinfectant Levels

* * * * *

§ 141.64 Maximum contaminant levels fordisinfection byproducts.

(a) The maximum contaminant levels(MCLs) for disinfection byproducts areas follows:

Disinfection byproduct MCL(mg/L)

Total trihalomethanes (TTHM) ........ 0.080Haloacetic acids (five) (HAA5) ....... 0.060Bromate .......................................... 0.010Chlorite ............................................ 1.0

(b) Compliance dates. (1) CWSs andNTNCWSs. Subpart H systems serving10,000 or more persons must complywith this section beginning December16, 2001. Subpart H systems servingfewer than 10,000 persons and systemsusing only ground water not under thedirect influence of surface water mustcomply with this section beginningDecember 16, 2003.

(2) A system that is installing GAC ormembrane technology to comply withthis section may apply to the State foran extension of up to 24 months past thedates in paragraphs (b)(1) of this section,but not beyond December 16, 2003. Ingranting the extension, States must seta schedule for compliance and mayspecify any interim measures that the

system must take. Failure to meet theschedule or interim treatmentrequirements constitutes a violation of aNational Primary Drinking WaterRegulation.

(c) The Administrator, pursuant toSection 1412 of the Act, herebyidentifies the following as the besttechnology, treatment techniques, orother means available for achievingcompliance with the maximumcontaminant levels for disinfectionbyproducts identified in paragraph (a) ofthis section:

Disinfec-tion by-product

Best available technology

TTHM ... Enhanced coagulation or en-hanced softening or GAC10,with chlorine as the primary andresidual disinfectant

HAA5 .... Enhanced coagulation or en-hanced softening or GAC10,with chlorine as the primary andresidual disinfectant.

Bromate Control of ozone treatment proc-ess to reduce production of bro-mate.

Chlorite Control of treatment processes toreduce disinfectant demand andcontrol of disinfection treatmentprocesses to reduce disinfectantlevels.

§ 141.65 Maximum residual disinfectantlevels.

(a) Maximum residual disinfectantlevels (MRDLs) are as follows:

Disinfectant residual MRDL (mg/L)

Chlorine ............................... 4.0 (as Cl2).Chloramines ......................... 4.0 (as Cl2).Chlorine dioxide ................... 0.8 (as ClO2).

(b) Compliance dates.(1) CWSs and NTNCWSs. Subpart H

systems serving 10,000 or more personsmust comply with this sectionbeginning December 16, 2001. SubpartH systems serving fewer than 10,000persons and systems using only groundwater not under the direct influence ofsurface water must comply with thissubpart beginning December 16, 2003.

(2) Transient NCWSs. Subpart Hsystems serving 10,000 or more personsand using chlorine dioxide as adisinfectant or oxidant must complywith the chlorine dioxide MRDLbeginning December 16, 2001. SubpartH systems serving fewer than 10,000persons and using chlorine dioxide as adisinfectant or oxidant and systemsusing only ground water not under thedirect influence of surface water andusing chlorine dioxide as a disinfectantor oxidant must comply with the


chlorine dioxide MRDL beginningDecember 16, 2003.

(c) The Administrator, pursuant toSection 1412 of the Act, herebyidentifies the following as the besttechnology, treatment techniques, orother means available for achievingcompliance with the maximum residualdisinfectant levels identified inparagraph (a) of this section: control oftreatment processes to reducedisinfectant demand and control ofdisinfection treatment processes toreduce disinfectant levels.

10. A new subpart L is added to readas follows:

Subpart L—Disinfectant Residuals,Disinfection Byproducts, andDisinfection Byproduct Precursors

Sec.141.130 General requirements.141.131 Analytical requirements.141.132 Monitoring requirements.141.133 Compliance requirements.141.134 Reporting and recordkeepingrequirements.141.135 Treatment technique for control ofdisinfection byproduct (DBP) precursors.

§ 141.130 General requirements.

(a) The requirements of this subpart Lconstitute national primary drinkingwater regulations.

(1) The regulations in this subpartestablish criteria under whichcommunity water systems (CWSs) andnontransient, noncommunity watersystems (NTNCWSs) which add achemical disinfectant to the water inany part of the drinking water treatmentprocess must modify their practices tomeet MCLs and MRDLs in §§ 141.64 and141.65, respectively, and must meet thetreatment technique requirements fordisinfection byproduct precursors in§ 141.135.

(2) The regulations in this subpartestablish criteria under which transientNCWSs that use chlorine dioxide as adisinfectant or oxidant must modifytheir practices to meet the MRDL forchlorine dioxide in § 141.65.

(3) EPA has established MCLs forTTHM and HAA5 and treatmenttechnique requirements for disinfectionbyproduct precursors to limit the levelsof known and unknown disinfectionbyproducts which may have adversehealth effects. These disinfectionbyproducts may include chloroform;bromodichloromethane;dibromochloromethane; bromoform;dichloroacetic acid; and trichloroaceticacid.

(b) Compliance dates. (1) CWSs andNTNCWSs. Unless otherwise noted,systems must comply with the

requirements of this subpart as follows.Subpart H systems serving 10,000 ormore persons must comply with thissubpart beginning December 16, 2001.Subpart H systems serving fewer than10,000 persons and systems using onlyground water not under the directinfluence of surface water must complywith this subpart beginning December16, 2003.

(2) Transient NCWSs. Subpart Hsystems serving 10,000 or more personsand using chlorine dioxide as adisinfectant or oxidant must complywith any requirements for chlorinedioxide and chlorite in this subpartbeginning December 16, 2001. SubpartH systems serving fewer than 10,000persons and using chlorine dioxide as adisinfectant or oxidant and systemsusing only ground water not under thedirect influence of surface water andusing chlorine dioxide as a disinfectantor oxidant must comply with anyrequirements for chlorine dioxide andchlorite in this subpart beginningDecember 16, 2003.

(c) Each CWS and NTNCWS regulatedunder paragraph (a) of this section mustbe operated by qualified personnel whomeet the requirements specified by theState and are included in a State registerof qualified operators.

(d) Control of disinfectant residuals.Notwithstanding the MRDLs in § 141.65,systems may increase residualdisinfectant levels in the distributionsystem of chlorine or chloramines (butnot chlorine dioxide) to a level and fora time necessary to protect publichealth, to address specificmicrobiological contamination problemscaused by circumstances such as, butnot limited to, distribution line breaks,storm run-off events, source watercontamination events, or cross-connection events.

§ 141.131 Analytical requirements.

(a) General. (1) Systems must use onlythe analytical method(s) specified inthis section, or otherwise approved byEPA for monitoring under this subpart,to demonstrate compliance with therequirements of this subpart. Thesemethods are effective for compliancemonitoring February 16, 1999.

(2) The following documents areincorporated by reference. The Directorof the Federal Register approves thisincorporation by reference inaccordance with 5 U.S.C. 552(a) and 1CFR part 51. Copies may be inspectedat EPA’s Drinking Water Docket, 401 MStreet, SW, Washington, DC 20460, or atthe Office of the Federal Register, 800North Capitol Street, NW, Suite 700,Washington DC. EPA Method 552.1 is in

Methods for the Determination ofOrganic Compounds in Drinking Water-Supplement II, USEPA, August 1992,EPA/600/R–92/129 (available throughNational Information Technical Service(NTIS), PB92–207703). EPA Methods502.2, 524.2, 551.1, and 552.2 are inMethods for the Determination ofOrganic Compounds in Drinking Water-Supplement III, USEPA, August 1995,EPA/600/R–95/131. (available throughNTIS, PB95–261616). EPA Method300.0 is in Methods for theDetermination of Inorganic Substancesin Environmental Samples, USEPA,August 1993, EPA/600/R–93/100.(available through NTIS, PB94–121811).EPA Method 300.1 is titled USEPAMethod 300.1, Determination ofInorganic Anions in Drinking Water byIon Chromatography, Revision 1.0,USEPA, 1997, EPA/600/R–98/118(available through NTIS, PB98-169196);also available from: Chemical ExposureResearch Branch, Microbiological &Chemical Exposure AssessmentResearch Division, National ExposureResearch Laboratory, U.S.Environmental Protection Agency,Cincinnati, OH 45268, Fax Number:513–569–7757, Phone number: 513–569–7586. Standard Methods 4500-Cl D,4500-Cl E, 4500-Cl F, 4500-Cl G, 4500-Cl H, 4500-Cl I, 4500-ClO2 D, 4500-ClO2

E, 6251 B, and 5910 B shall be followedin accordance with Standard Methodsfor the Examination of Water andWastewater, 19th Edition, AmericanPublic Health Association, 1995; copiesmay be obtained from the AmericanPublic Health Association, 1015Fifteenth Street, NW, Washington, DC20005. Standard Methods 5310 B, 5310C, and 5310 D shall be followed inaccordance with the Supplement to the19th Edition of Standard Methods forthe Examination of Water andWastewater, American Public HealthAssociation, 1996; copies may beobtained from the American PublicHealth Association, 1015 FifteenthStreet, NW, Washington, DC 20005.ASTM Method D 1253–86 shall befollowed in accordance with the AnnualBook of ASTM Standards, Volume11.01, American Society for Testing andMaterials, 1996 edition; copies may beobtained from the American Society forTesting and Materials, 100 Barr HarborDrive, West Conshohoken, PA 19428.

(b) Disinfection byproducts. (1)Systems must measure disinfectionbyproducts by the methods (as modifiedby the footnotes) listed in the followingtable:


APPROVED METHODS FOR DISINFECTION BYPRODUCT COMPLIANCE MONITORING

Methodology 2 EPA meth-od Standard method

Byproduct measured 1

TTHM HAA5 Chlorite 4 Bromate

P&T/GC/ElCD & PID ......................................... 3502.2 XP&T/GC/MS ...................................................... 524.2 XLLE/GC/ECD ..................................................... 551.1 XLLE/GC/ECD ..................................................... 6251 B XSPE/GC/ECD .................................................... 552.1 XLLE/GC/ECD ..................................................... 552.2 XAmperometric Titration ...................................... 4500-ClO2 E XIC ....................................................................... 300.0 XIC ....................................................................... 300.1 X X

1 X indicates method is approved for measuring specified disinfection byproduct.2 P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID = photoionization detector; MS = mass spec-

trometer; LLE = liquid/liquid extraction; ECD = electron capture detector; SPE = solid phase extractor; IC = ion chromatography.3 If TTHMs are the only analytes being measured in the sample, then a PID is not required.4 Amperometric titration may be used for routine daily monitoring of chlorite at the entrance to the distribution system, as prescribed in

§ 141.132(b)(2)(i)(A). Ion chromatography must be used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the dis-tribution system, as prescribed in § 141.132(b)(2)(i)(B) and (b)(2)(ii).

(2) Analysis under this section fordisinfection byproducts must beconducted by laboratories that havereceived certification by EPA or theState. To receive certification to conductanalyses for the contaminants in§ 141.64(a), the laboratory must carryout annual analyses of performanceevaluation (PE) samples approved by

EPA or the State. In these analyses of PEsamples, the laboratory must achievequantitative results within theacceptance limit on a minimum of 80%of the analytes included in each PEsample. The acceptance limit is definedas the 95% confidence intervalcalculated around the mean of the PEstudy data between a maximum and

minimum acceptance limit of +/¥50%and +/¥15% of the study mean.

(c) Disinfectant residuals. (1) Systemsmust measure residual disinfectantconcentrations for free chlorine,combined chlorine (chloramines), andchlorine dioxide by the methods listedin the following table:

APPROVED METHODS FOR DISINFECTANT RESIDUAL COMPLIANCE MONITORING

Methodology Standardmethod ASTM method

Residual Measured 1

Freechlorine

Combinedchlorine

Totalchlorine

Chlorinedioxide

Amperometric Titration ........................................ 4500-Cl D D 1253–86 X X XLow Level Amperometric Titration ...................... 4500-Cl E XDPD Ferrous Titrimetric ...................................... 4500-Cl F X X XDPD Colorimetric ................................................ 4500-Cl G X X XSyringaldazin e (FACTS) .................................... 4500-Cl H XIodometric Electrode ........................................... 4500-Cl I XDPD ..................................................................... 4500-ClO2 D XAmperometric Method II ..................................... 4500-ClO2 E X

1 X indicates method is approved for measuring specified disinfectant residual.

(2) If approved by the State, systemsmay also measure residual disinfectantconcentrations for chlorine,chloramines, and chlorine dioxide byusing DPD colorimetric test kits.

(3) A party approved by EPA or theState must measure residual disinfectantconcentration.

(d) Additional analytical methods.Systems required to analyze parametersnot included in paragraphs (b) and (c)of this section must use the followingmethods. A party approved by EPA orthe State must measure theseparameters.

(1) Alkalinity. All methods allowed in§ 141.89(a) for measuring alkalinity.

(2) Bromide. EPA Method 300.0 orEPA Method 300.1.

(3) Total Organic Carbon (TOC).Standard Method 5310 B (High-Temperature Combustion Method) orStandard Method 5310 C (Persulfate-Ultraviolet or Heated-PersulfateOxidation Method) or Standard Method5310 D (Wet-Oxidation Method). TOCsamples may not be filtered prior toanalysis. TOC samples must either beanalyzed or must be acidified to achievepH less than 2.0 by minimal addition ofphosphoric or sulfuric acid as soon aspractical after sampling, not to exceed24 hours. Acidified TOC samples mustbe analyzed within 28 days.

(4) Specific Ultraviolet Absorbance(SUVA). SUVA is equal to the UVabsorption at 254nm (UV254) (measuredin m-1 divided by the dissolved organiccarbon (DOC) concentration (measured

as mg/L). In order to determine SUVA,it is necessary to separately measureUV254 and DOC. When determiningSUVA, systems must use the methodsstipulated in paragraph (d)(4)(i) of thissection to measure DOC and the methodstipulated in paragraph (d)(4)(ii) of thissection to measure UV254. SUVA mustbe determined on water prior to theaddition of disinfectants/oxidants by thesystem. DOC and UV254 samples used todetermine a SUVA value must be takenat the same time and at the samelocation.

(i) Dissolved Organic Carbon (DOC).Standard Method 5310 B (High-Temperature Combustion Method) orStandard Method 5310 C (Persulfate-Ultraviolet or Heated-PersulfateOxidation Method) or Standard Method


5310 D (Wet-Oxidation Method). Priorto analysis, DOC samples must befiltered through a 0.45 µm pore-diameterfilter. Water passed through the filterprior to filtration of the sample mustserve as the filtered blank. This filteredblank must be analyzed usingprocedures identical to those used foranalysis of the samples and must meetthe following criteria: DOC < 0.5 mg/L.DOC samples must be filtered throughthe 0.45 µm pore-diameter filter prior toacidification. DOC samples must eitherbe analyzed or must be acidified toachieve pH less than 2.0 by minimaladdition of phosphoric or sulfuric acidas soon as practical after sampling, notto exceed 48 hours. Acidified DOCsamples must be analyzed within 28days.

(ii) Ultraviolet Absorption at 254 nm(UV254). Method 5910 B (UltravioletAbsorption Method). UV absorption

must be measured at 253.7 nm (may berounded off to 254 nm). Prior toanalysis, UV254 samples must be filteredthrough a 0.45 µm pore-diameter filter.The pH of UV254 samples may not beadjusted. Samples must be analyzed assoon as practical after sampling, not toexceed 48 hours.

(5) pH. All methods allowed in§ 141.23(k)(1) for measuring pH.

§ 141.132 Monitoring requirements.

(a) General requirements. (1) Systemsmust take all samples during normaloperating conditions.

(2) Systems may consider multiplewells drawing water from a singleaquifer as one treatment plant fordetermining the minimum number ofTTHM and HAA5 samples required,with State approval in accordance withcriteria developed under § 142.16(f)(5)of this chapter.

(3) Failure to monitor in accordancewith the monitoring plan requiredunder paragraph (f) of this section is amonitoring violation.

(4) Failure to monitor will be treatedas a violation for the entire periodcovered by the annual average wherecompliance is based on a runningannual average of monthly or quarterlysamples or averages and the system’sfailure to monitor makes it impossible todetermine compliance with MCLs orMRDLs.

(5) Systems may use only datacollected under the provisions of thissubpart or subpart M of this part toqualify for reduced monitoring.

(b) Monitoring requirements fordisinfection byproducts. (1) TTHMs andHAA5. (i) Routine monitoring. Systemsmust monitor at the frequency indicatedin the following table:

ROUTINE MONITORING FREQUENCY FOR TTHM AND HAA5

Type of system Minimum monitoring frequency Sample location in the distribution system

Subpart H system serving at least10,000 persons.

Four water samples per quarterper treatment plant.

At least 25 percent of all samples collected each quarter at locationsrepresenting maximum residence time. Remaining samples taken atlocations representative of at least average residence time in thedistribution system and representing the entire distribution system,taking into account number of persons served, different sources ofwater, and different treatment methods.1

Subpart H system serving from500 to 9,999 persons.

One water sample per quarter pertreatment plant.

Locations representing maximum residence time.1

Subpart H system serving fewerthan 500 persons.

One sample per year per treat-ment plant during month ofwarmest water temperature.

Locations representing maximum residence time.1 If the sample (oraverage of annual samples, if more than one sample is taken) ex-ceeds MCL, system must increase monitoring to one sample pertreatment plant per quarter, taken at a point reflecting the maximumresidence time in the distribution system, until system meets re-duced monitoring criteria in paragraph (c) of this section.

System using only ground waternot under direct influence of sur-face water using chemical dis-infectant and serving at least10,000 persons.

One water sample per quarter pertreatment plant 2.

Locations representing maximum residence time.1

System using only ground waternot under direct influence of sur-face water using chemical dis-infectant and serving fewer than10,000 persons.

One sample per year per treat-ment plant 2 during month ofwarmest water temperature.

Locations representing maximum residence time.1 If the sample (oraverage of annual samples, if more than one sample is taken) ex-ceeds MCL, system must increase monitoring to one sample pertreatment plant per quarter, taken at a point reflecting the maximumresidence time in the distribution system, until system meets criteriain paragraph (c) of this section for reduced monitoring.

1 If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples collected each quarter (includingthose taken in excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the dis-tribution system. The remaining samples must be taken at locations representative of at least average residence time in the distribution system.

2 Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the minimum number of samplesrequired, with State approval in accordance with criteria developed under § 142.16(f)(5) of this chapter.

(ii) Systems may reduce monitoring,except as otherwise provided, inaccordance with the following table:


Reduced Monitoring Frequency for TTHM and HAA5

If you are a . . .You may reduce monitoring if youhave monitored at least one year

and your . . .To this level

Subpart H system serving at least10,000 persons which has asource water annual averageTOC level, before any treatment,≤4.0 mg/L.

TTHM annual average ≤0.040 mg/L and HAA5 annual average≤0.030 mg/L.

One sample per treatment plant per quarter at distribution system lo-cation reflecting maximum residence time.

Subpart H system serving from500 to 9,999 persons which hasa source water annual averageTOC level, before any treatment,≤4.0 mg/L.


One sample per treatment plant per year at distribution system loca-tion reflecting maximum residence time during month of warmestwater temperature. NOTE: Any Subpart H system serving fewerthan 500 persons may not reduce its monitoring to less than onesample per treatment plant per year.

System using only ground waternot under direct influence of sur-face water using chemical dis-infectant and serving at least10,000 persons.


One sample per treatment plant per year at distribution system loca-tion reflecting maximum residence time during month of warmestwater temperature

System using only ground waternot under direct influence of sur-face water using chemical dis-infectant and serving fewer than10,000 persons.

TTHM annual average ≤0.040 mg/L and HAA5 annual average≤0.030 mg/L for two consecutiveyears OR TTHM annual average≤0.020 mg/L and HAA5 annualaverage ≤0.015 mg/L for oneyear.

One sample per treatment plant per three year monitoring cycle atdistribution system location reflecting maximum residence time dur-ing month of warmest water temperature, with the three-year cyclebeginning on January 1 following quarter in which system qualifiesfor reduced monitoring.

(iii) Systems on a reduced monitoringschedule may remain on that reducedschedule as long as the average of allsamples taken in the year (for systemswhich must monitor quarterly) or theresult of the sample (for systems whichmust monitor no more frequently thanannually) is no more than 0.060 mg/Land 0.045 mg/L for TTHMs and HAA5,respectively. Systems that do not meetthese levels must resume monitoring atthe frequency identified in paragraph(b)(1)(i) of this section in the quarterimmediately following the quarter inwhich the system exceeds 0.060 mg/Land 0.045 mg/L for TTHMs and HAA5,respectively.

(iv) The State may return a system toroutine monitoring at the State’sdiscretion.

(2) Chlorite. Community andnontransient noncommunity watersystems using chlorine dioxide, fordisinfection or oxidation, must conductmonitoring for chlorite.

(i) Routine monitoring. (A) Dailymonitoring. Systems must take dailysamples at the entrance to thedistribution system. For any dailysample that exceeds the chlorite MCL,the system must take additional samplesin the distribution system the followingday at the locations required byparagraph (b)(2)(ii) of this section, inaddition to the sample required at theentrance to the distribution system.

(B) Monthly monitoring. Systems musttake a three-sample set each month inthe distribution system. The systemmust take one sample at each of thefollowing locations: near the first

customer, at a location representative ofaverage residence time, and at a locationreflecting maximum residence time inthe distribution system. Any additionalroutine sampling must be conducted inthe same manner (as three-sample sets,at the specified locations). The systemmay use the results of additionalmonitoring conducted under paragraph(b)(2)(ii) of this section to meet therequirement for monitoring in thisparagraph.

(ii) Additional monitoring. On eachday following a routine samplemonitoring result that exceeds thechlorite MCL at the entrance to thedistribution system, the system isrequired to take three chloritedistribution system samples at thefollowing locations: as close to the firstcustomer as possible, in a locationrepresentative of average residence time,and as close to the end of thedistribution system as possible(reflecting maximum residence time inthe distribution system).

(iii) Reduced monitoring. (A) Chloritemonitoring at the entrance to thedistribution system required byparagraph (b)(2)(i)(A) of this sectionmay not be reduced.

(B) Chlorite monitoring in thedistribution system required byparagraph (b)(2)(i)(B) of this section maybe reduced to one three-sample set perquarter after one year of monitoringwhere no individual chlorite sampletaken in the distribution system underparagraph (b)(2)(i)(B) of this section hasexceeded the chlorite MCL and thesystem has not been required to conduct

monitoring under paragraph (b)(2)(ii) ofthis section. The system may remain onthe reduced monitoring schedule untileither any of the three individualchlorite samples taken quarterly in thedistribution system under paragraph(b)(2)(i)(B) of this section exceeds thechlorite MCL or the system is requiredto conduct monitoring under paragraph(b)(2)(ii) of this section, at which timethe system must revert to routinemonitoring.

(3) Bromate. (i) Routine monitoring.Community and nontransientnoncommunity systems using ozone, fordisinfection or oxidation, must take onesample per month for each treatmentplant in the system using ozone.Systems must take samples monthly atthe entrance to the distribution systemwhile the ozonation system is operatingunder normal conditions.

(ii) Reduced monitoring. Systemsrequired to analyze for bromate mayreduce monitoring from monthly toonce per quarter, if the systemdemonstrates that the average sourcewater bromide concentration is less than0.05 mg/L based upon representativemonthly bromide measurements for oneyear. The system may remain onreduced bromate monitoring until therunning annual average source waterbromide concentration, computedquarterly, is equal to or greater than 0.05mg/L based upon representativemonthly measurements. If the runningannual average source water bromideconcentration is ≥0.05 mg/L, the systemmust resume routine monitoring


required by paragraph (b)(3)(i) of thissection.

(c) Monitoring requirements fordisinfectant residuals. (1) Chlorine andchloramines. (i) Routine monitoring.Systems must measure the residualdisinfectant level at the same points inthe distribution system and at the sametime as total coliforms are sampled, asspecified in § 141.21. Subpart H systemsmay use the results of residualdisinfectant concentration samplingconducted under § 141.74(b)(6)(i) forunfiltered systems or § 141.74(c)(3)(i) forsystems which filter, in lieu of takingseparate samples.

(ii) Reduced monitoring. Monitoringmay not be reduced.

(2) Chlorine dioxide. (i) Routinemonitoring. Community, nontransientnoncommunity, and transientnoncommunity water systems that usechlorine dioxide for disinfection oroxidation must take daily samples at theentrance to the distribution system. Forany daily sample that exceeds theMRDL, the system must take samples inthe distribution system the followingday at the locations required byparagraph (c)(2)(ii) of this section, inaddition to the sample required at theentrance to the distribution system.

(ii) Additional monitoring. On eachday following a routine samplemonitoring result that exceeds theMRDL, the system is required to takethree chlorine dioxide distributionsystem samples. If chlorine dioxide orchloramines are used to maintain adisinfectant residual in the distributionsystem, or if chlorine is used tomaintain a disinfectant residual in thedistribution system and there are nodisinfection addition points after theentrance to the distribution system (i.e.,no booster chlorination), the systemmust take three samples as close to thefirst customer as possible, at intervals ofat least six hours. If chlorine is used tomaintain a disinfectant residual in thedistribution system and there are one ormore disinfection addition points afterthe entrance to the distribution system(i.e., booster chlorination), the systemmust take one sample at each of thefollowing locations: as close to the firstcustomer as possible, in a locationrepresentative of average residence time,and as close to the end of thedistribution system as possible(reflecting maximum residence time inthe distribution system).

(iii) Reduced monitoring. Chlorinedioxide monitoring may not be reduced.

(d) Monitoring requirements fordisinfection byproduct precursors(DBPP). (1) Routine monitoring. SubpartH systems which use conventionalfiltration treatment (as defined in

§ 141.2) must monitor each treatmentplant for TOC no later than the point ofcombined filter effluent turbiditymonitoring and representative of thetreated water. All systems required tomonitor under this paragraph (d)(1)must also monitor for TOC in the sourcewater prior to any treatment at the sametime as monitoring for TOC in thetreated water. These samples (sourcewater and treated water) are referred toas paired samples. At the same time asthe source water sample is taken, allsystems must monitor for alkalinity inthe source water prior to any treatment.Systems must take one paired sampleand one source water alkalinity sampleper month per plant at a timerepresentative of normal operatingconditions and influent water quality.

(2) Reduced monitoring. Subpart Hsystems with an average treated waterTOC of less than 2.0 mg/L for twoconsecutive years, or less than 1.0 mg/L for one year, may reduce monitoringfor both TOC and alkalinity to onepaired sample and one source wateralkalinity sample per plant per quarter.The system must revert to routinemonitoring in the month following thequarter when the annual average treatedwater TOC ≥2.0 mg/L.

(e) Bromide. Systems required toanalyze for bromate may reduce bromatemonitoring from monthly to once perquarter, if the system demonstrates thatthe average source water bromideconcentration is less than 0.05 mg/Lbased upon representative monthlymeasurements for one year. The systemmust continue bromide monitoring toremain on reduced bromate monitoring.

(f) Monitoring plans. Each systemrequired to monitor under this subpartmust develop and implement amonitoring plan. The system mustmaintain the plan and make it availablefor inspection by the State and thegeneral public no later than 30 daysfollowing the applicable compliancedates in § 141.130(b). All Subpart Hsystems serving more than 3300 peoplemust submit a copy of the monitoringplan to the State no later than the dateof the first report required under§ 141.134. The State may also requirethe plan to be submitted by any othersystem. After review, the State mayrequire changes in any plan elements.The plan must include at least thefollowing elements.

(1) Specific locations and schedulesfor collecting samples for anyparameters included in this subpart.

(2) How the system will calculatecompliance with MCLs, MRDLs, andtreatment techniques.

(3) If approved for monitoring as aconsecutive system, or if providing

water to a consecutive system, under theprovisions of § 141.29, the samplingplan must reflect the entire distributionsystem.

§ 141.133 Compliance requirements.(a) General requirements. (1) Where

compliance is based on a runningannual average of monthly or quarterlysamples or averages and the system’sfailure to monitor for TTHM, HAA5, orbromate, this failure to monitor will betreated as a monitoring violation for theentire period covered by the annualaverage. Where compliance is based ona running annual average of monthly orquarterly samples or averages and thesystem’s failure to monitor makes itimpossible to determine compliancewith MRDLs for chlorine andchloramines, this failure to monitor willbe treated as a monitoring violation forthe entire period covered by the annualaverage.

(2) All samples taken and analyzedunder the provisions of this subpartmust be included in determiningcompliance, even if that number isgreater than the minimum required.

(3) If, during the first year ofmonitoring under § 141.132, anyindividual quarter’s average will causethe running annual average of thatsystem to exceed the MCL, the systemis out of compliance at the end of thatquarter.

(b) Disinfection byproducts. (1)TTHMs and HAA5. (i) For systemsmonitoring quarterly, compliance withMCLs in § 141.64 must be based on arunning annual arithmetic average,computed quarterly, of quarterlyarithmetic averages of all samplescollected by the system as prescribed by§ 141.132(b)(1). If the running annualarithmetic average of quarterly averagescovering any consecutive four-quarterperiod exceeds the MCL, the system isin violation of the MCL and must notifythe public pursuant to § 141.32, inaddition to reporting to the Statepursuant to § 141.134. If a PWS fails tocomplete four consecutive quarters’monitoring, compliance with the MCLfor the last four-quarter complianceperiod must be based on an average ofthe available data.

(ii) For systems monitoring lessfrequently than quarterly, compliancemust be based on an average of samplestaken that year under the provisions of§ 141.132(b)(1). If the average of thesesamples exceeds the MCL, the systemmust increase monitoring to once perquarter per treatment plant.

(iii) Systems on a reduced monitoringschedule whose annual average exceedsthe MCL will revert to routinemonitoring immediately. These systems


will not be considered in violation ofthe MCL until they have completed oneyear of routine monitoring.

(2). Bromate. Compliance must bebased on a running annual arithmeticaverage, computed quarterly, of monthlysamples (or, for months in which thesystem takes more than one sample, theaverage of all samples taken during themonth) collected by the system asprescribed by § 141.132(b)(3). If theaverage of samples covering anyconsecutive four-quarter period exceedsthe MCL, the system is in violation ofthe MCL and must notify the publicpursuant to § 141.32, in addition toreporting to the State pursuant to§ 141.134. If a PWS fails to complete 12consecutive months’ monitoring,compliance with the MCL for the lastfour-quarter compliance period must bebased on an average of the availabledata.

(3) Chlorite. Compliance must bebased on an arithmetic average of eachthree sample set taken in thedistribution system as prescribed by§ 141.132(b)(2)(i)(B) and§ 141.132(b)(2)(ii). If the arithmeticaverage of any three sample set exceedsthe MCL, the system is in violation ofthe MCL and must notify the publicpursuant to § 141.32, in addition toreporting to the State pursuant to§ 141.134.

(c) Disinfectant residuals. (1) Chlorineand chloramines. (i) Compliance mustbe based on a running annual arithmeticaverage, computed quarterly, of monthlyaverages of all samples collected by thesystem under § 141.132(c)(1). If theaverage of quarterly averages coveringany consecutive four-quarter periodexceeds the MRDL, the system is inviolation of the MRDL and must notifythe public pursuant to § 141.32, inaddition to reporting to the Statepursuant to § 141.134.

(ii) In cases where systems switchbetween the use of chlorine and

chloramines for residual disinfectionduring the year, compliance must bedetermined by including together allmonitoring results of both chlorine andchloramines in calculating compliance.Reports submitted pursuant to § 141.134must clearly indicate which residualdisinfectant was analyzed for eachsample.

(2) Chlorine dioxide. (i) Acuteviolations. Compliance must be basedon consecutive daily samples collectedby the system under § 141.132(c)(2). Ifany daily sample taken at the entranceto the distribution system exceeds theMRDL, and on the following day one (ormore) of the three samples taken in thedistribution system exceed the MRDL,the system is in violation of the MRDLand must take immediate correctiveaction to lower the level of chlorinedioxide below the MRDL and mustnotify the public pursuant to theprocedures for acute health risks in§ 141.32(a)(1)(iii)(E). Failure to takesamples in the distribution system theday following an exceedance of thechlorine dioxide MRDL at the entranceto the distribution system will also beconsidered an MRDL violation and thesystem must notify the public of theviolation in accordance with theprovisions for acute violations under§ 141.32(a)(1)(iii)(E).

(ii) Nonacute violations. Compliancemust be based on consecutive dailysamples collected by the system under§ 141.132(c)(2). If any two consecutivedaily samples taken at the entrance tothe distribution system exceed theMRDL and all distribution systemsamples taken are below the MRDL, thesystem is in violation of the MRDL andmust take corrective action to lower thelevel of chlorine dioxide below theMRDL at the point of sampling and willnotify the public pursuant to theprocedures for nonacute health risks in§ 141.32(e)(78). Failure to monitor at theentrance to the distribution system the

day following an exceedance of thechlorine dioxide MRDL at the entranceto the distribution system is also anMRDL violation and the system mustnotify the public of the violation inaccordance with the provisions fornonacute violations under§ 141.32(e)(78).

(d) Disinfection byproduct precursors(DBPP). Compliance must bedetermined as specified by § 141.135(b).Systems may begin monitoring todetermine whether Step 1 TOCremovals can be met 12 months prior tothe compliance date for the system. Thismonitoring is not required and failure tomonitor during this period is not aviolation. However, any system thatdoes not monitor during this period,and then determines in the first 12months after the compliance date that itis not able to meet the Step 1requirements in § 141.135(b)(2) andmust therefore apply for alternateminimum TOC removal (Step 2)requirements, is not eligible forretroactive approval of alternateminimum TOC removal (Step 2)requirements as allowed pursuant to§ 141.135(b)(3) and is in violation.Systems may apply for alternateminimum TOC removal (Step 2)requirements any time after thecompliance date.

§ 141.134 Reporting and recordkeepingrequirements.

(a) Systems required to samplequarterly or more frequently must reportto the State within 10 days after the endof each quarter in which samples werecollected, notwithstanding theprovisions of § 141.31. Systems requiredto sample less frequently than quarterlymust report to the State within 10 daysafter the end of each monitoring periodin which samples were collected.

(b) Disinfection byproducts. Systemsmust report the information specified inthe following table:

If you are a... You must report...1

System monitoring for TTHM and HAA5 under the requirements of§§ 141.132(b) on a quarterly or more frequent basis.

(1) The number of samples taken during the last quarter.

(2) The location, date, and result of each sample taken during the lastquarter.

(3) The arithmetic average of all samples taken in the last quarter.(4) The annual arithmetic average of the quarterly arithmetic averages

of this section for the last four quarters.(5) Whether the MCL was exceeded.

System monitoring for TTHMs and HAA5 under the requirements of§§ 141.132(b) less frequently than quarterly (but at least annually).

(1) The number of samples taken during the last year.


(3) The arithmetic average of all samples taken over the last year.(4) Whether the MCL was exceeded.

System monitoring for TTHMs and HAA5 under the requirements of§ 141.132(b) less frequently than annually.

(1) The location, date, and result of the last sample taken.

(2) Whether the MCL was exceeded.



System monitoring for chlorite under the requirements of § 141.132(b) .. (1) The number of samples taken each month for the last 3 months.(2) The location, date, and result of each sample taken during the last

quarter.(3) For each month in the reporting period, the arithmetic average of all

samples taken in the month.(4) Whether the MCL was exceeded, and in which month it was ex-

ceeded.System monitoring for bromate under the requirements of § 141.132(b) (1) The number of samples taken during the last quarter.


(3) The arithmetic average of the monthly arithmetic averages of allsamples taken in the last year.

(4) Whether the MCL was exceeded.

(c) Disinfectants. Systems must reportthe information specified in thefollowing table:


System monitoring for chlorine or chloramines under the requirementsof § 141.132(c).

(1) The number of samples taken during each month of the last quar-ter.

(2) The monthly arithmetic average of all samples taken in each monthfor the last 12 months.

(3) The arithmetic average of all monthly averages for the last 12months.

(4) Whether the MRDL was exceeded.System monitoring for chlorine dioxide under the requirements of

§ 141.132(c).(1) The dates, results, and locations of samples taken during the last

quarter.(2) Whether the MRDL was exceeded.(3) Whether the MRDL was exceeded in any two consecutive daily

samples and whether the resulting violation was acute or nonacute.

1 The State may choose to perform calculations and determine whether the MRDL was exceeded, in lieu of having the system report that infor-mation.

(d) Disinfection byproduct precursorsand enhanced coagulation or enhancedsoftening. Systems must report the

information specified in the followingtable:

If you are a . . . You must report . . .1

System monitoring monthly or quarterly for TOC under the require-ments of § 141.132(d) and required to meet the enhanced coagula-tion or enhanced softening requirements in § 141.135(b)(2) or (3).

(1) The number of paired (source water and treated water, prior to con-tinuous disinfection) samples taken during the last quarter.

(2) The location, date, and result of each paired sample and associ-ated alkalinity taken during the last quarter.

(3) For each month in the reporting period that paired samples weretaken, the arithmetic average of the percent reduction of TOC foreach paired sample and the required TOC percent removal.

(4) Calculations for determining compliance with the TOC percent re-moval requirements, as provided in § 141.135(c)(1).

(5) Whether the system is in compliance with the enhanced coagula-tion or enhanced softening percent removal requirements in§ 141.135(b) for the last four quarters.

System monitoring monthly or quarterly for TOC under the require-ments of § 141.132(d) and meeting one or more of the alternativecompliance criteria in § 141.135(a)(2) or (3).

(1) The alternative compliance criterion that the system is using.

(2) The number of paired samples taken during the last quarter.(3) The location, date, and result of each paired sample and associ-

ated alkalinity taken during the last quarter.(4) The running annual arithmetic average based on monthly averages

(or quarterly samples) of source water TOC for systems meeting acriterion in §§ 141.135(a)(2)(i) or (iii) or of treated water TOC for sys-tems meeting the criterion in § 141.135(a)(2)(ii).


If you are a . . . You must report . . .1

(5) The running annual arithmetic average based on monthly averages(or quarterly samples) of source water SUVA for systems meetingthe criterion in § 141.135(a)(2)(v) or of treated water SUVA for sys-tems meeting the criterion in § 141.135(a)(2)(vi).

(6) The running annual average of source water alkalinity for systemsmeeting the criterion in § 141.135(a)(2)(iii) and of treated water alka-linity for systems meeting the criterion in § 141.135(a)(3)(i).

(7) The running annual average for both TTHM and HAA5 for systemsmeeting the criterion in § 141.135(a)(2)(iii) or (iv).

(8) The running annual average of the amount of magnesium hardnessremoval (as CaCO3, in mg/L) for systems meeting the criterion in§ 141.135(a)(3)(ii).

(9) Whether the system is in compliance with the particular alternativecompliance criterion in § 141.135(a)(2) or (3).

1 The State may choose to perform calculations and determine whether the treatment technique was met, in lieu of having the system reportthat information.

§ 141.135 Treatment technique for controlof disinfection byproduct (DBP) precursors.

(a) Applicability. (1) Subpart Hsystems using conventional filtrationtreatment (as defined in § 141.2 ) mustoperate with enhanced coagulation orenhanced softening to achieve the TOCpercent removal levels specified inparagraph (b) of this section unless thesystem meets at least one of thealternative compliance criteria listed inparagraph (a)(2) or (a)(3) of this section.

(2) Alternative compliance criteria forenhanced coagulation and enhancedsoftening systems. Subpart H systemsusing conventional filtration treatmentmay use the alternative compliancecriteria in paragraphs (a)(2)(i) through(vi) of this section to comply with thissection in lieu of complying withparagraph (b) of this section. Systemsmust still comply with monitoringrequirements in § 141.132(d).

(i) The system’s source water TOClevel, measured according to§ 141.131(d)(3), is less than 2.0 mg/L,calculated quarterly as a running annualaverage.

(ii) The system’s treated water TOClevel, measured according to§ 141.131(d)(3), is less than 2.0 mg/L,calculated quarterly as a running annualaverage.

(iii) The system’s source water TOClevel, measured as required by§ 141.131(d)(3), is less than 4.0 mg/L,calculated quarterly as a running annualaverage; the source water alkalinity,measured according to § 141.131(d)(1),is greater than 60 mg/L (as CaCO3),calculated quarterly as a running annualaverage; and either the TTHM andHAA5 running annual averages are nogreater than 0.040 mg/L and 0.030 mg/

L, respectively; or prior to the effectivedate for compliance in § 141.130(b), thesystem has made a clear and irrevocablefinancial commitment not later than theeffective date for compliance in§ 141.130(b) to use of technologies thatwill limit the levels of TTHMs andHAA5 to no more than 0.040 mg/L and0.030 mg/L, respectively. Systems mustsubmit evidence of a clear andirrevocable financial commitment, inaddition to a schedule containingmilestones and periodic progress reportsfor installation and operation ofappropriate technologies, to the State forapproval not later than the effective datefor compliance in § 141.130(b). Thesetechnologies must be installed andoperating not later than June 16, 2005.Failure to install and operate thesetechnologies by the date in the approvedschedule will constitute a violation ofNational Primary Drinking WaterRegulations.

(iv) The TTHM and HAA5 runningannual averages are no greater than0.040 mg/L and 0.030 mg/L,respectively, and the system uses onlychlorine for primary disinfection andmaintenance of a residual in thedistribution system.

(v) The system’s source water SUVA,prior to any treatment and measuredmonthly according to § 141.131(d)(4), isless than or equal to 2.0 L/mg-m,calculated quarterly as a running annualaverage.

(vi) The system’s finished waterSUVA, measured monthly according to§ 141.131(d)(4), is less than or equal to2.0 L/mg-m, calculated quarterly as arunning annual average.

(3) Additional alternative compliancecriteria for softening systems. Systems

practicing enhanced softening thatcannot achieve the TOC removalsrequired by paragraph (b)(2) of thissection may use the alternativecompliance criteria in paragraphs(a)(3)(i) and (ii) of this section in lieu ofcomplying with paragraph (b) of thissection. Systems must still comply withmonitoring requirements in§ 141.132(d).

(i) Softening that results in loweringthe treated water alkalinity to less than60 mg/L (as CaCO3), measured monthlyaccording to § 141.131(d)(1) andcalculated quarterly as a running annualaverage.

(ii) Softening that results in removingat least 10 mg/L of magnesium hardness(as CaCO3), measured monthly andcalculated quarterly as an annualrunning average.

(b) Enhanced coagulation andenhanced softening performancerequirements. (1) Systems must achievethe percent reduction of TOC specifiedin paragraph (b)(2) of this sectionbetween the source water and thecombined filter effluent, unless the Stateapproves a system’s request for alternateminimum TOC removal (Step 2)requirements under paragraph (b)(3) ofthis section.

(2) Required Step 1 TOC reductions,indicated in the following table, arebased upon specified source waterparameters measured in accordancewith § 141.131(d). Systems practicingsoftening are required to meet the Step1 TOC reductions in the far-rightcolumn (Source water alkalinity >120mg/L) for the specified source waterTOC:


STEP 1 REQUIRED REMOVAL OF TOC BY ENHANCED COAGULATION AND ENHANCED SOFTENING FOR SUBPART HSYSTEMS USING CONVENTIONAL TREATMENT 1, 2

Source-water TOC, mg/L

Source-water alkalinity, mg/L as CaCO3

0–60 (percent) ≤60–120 (per-cent)

>120 3 (per-cent)

>2.0–4.0 ....................................................................................................................................... 35.0 25.0 15.0>4.0–8.0 ....................................................................................................................................... 45.0 35.0 25.0>8.0 .............................................................................................................................................. 50.0 40.0 30.0

1 Systems meeting at least one of the conditions in paragraph (a)(2)(i)–(vi) of this section are not required to operate with enhanced coagula-tion.

2 Softening systems meeting one of the alternative compliance criteria in paragraph (a)(3) of this section are not required to operate with en-hanced softening.

3 Systems practicing softening must meet the TOC removal requirements in this column.

(3) Subpart H conventional treatmentsystems that cannot achieve the Step 1TOC removals required by paragraph(b)(2) of this section due to water qualityparameters or operational constraintsmust apply to the State, within threemonths of failure to achieve the TOCremovals required by paragraph (b)(2) ofthis section, for approval of alternativeminimum TOC (Step 2) removalrequirements submitted by the system.If the State approves the alternativeminimum TOC removal (Step 2)requirements, the State may make thoserequirements retroactive for thepurposes of determining compliance.Until the State approves the alternateminimum TOC removal (Step 2)requirements, the system must meet theStep 1 TOC removals contained inparagraph (b)(2) of this section.

(4) Alternate minimum TOC removal(Step 2) requirements. Applicationsmade to the State by enhancedcoagulation systems for approval ofalternative minimum TOC removal(Step 2) requirements under paragraph(b)(3) of this section must include, as aminimum, results of bench- or pilot-scale testing conducted under paragraph(b)(4)(i) of this section and used todetermine the alternate enhancedcoagulation level.

(i) Alternate enhanced coagulationlevel is defined as coagulation at acoagulant dose and pH as determined bythe method described in paragraphs(b)(4)(i) through (v) of this section suchthat an incremental addition of 10 mg/L of alum (as aluminum) (or equivalentamount of ferric salt) results in a TOCremoval of ≤ 0.3 mg/L. The percentremoval of TOC at this point on the‘‘TOC removal versus coagulant dose’’curve is then defined as the minimumTOC removal required for the system.Once approved by the State, thisminimum requirement supersedes theminimum TOC removal required by thetable in paragraph (b)(2) of this section.This requirement will be effective untilsuch time as the State approves a new

value based on the results of a newbench- and pilot-scale test. Failure toachieve State-set alternative minimumTOC removal levels is a violation ofNational Primary Drinking WaterRegulations.

(ii) Bench- or pilot-scale testing ofenhanced coagulation must beconducted by using representative watersamples and adding 10 mg/L incrementsof alum (as aluminum) (or equivalentamounts of ferric salt) until the pH isreduced to a level less than or equal tothe enhanced coagulation Step 2 targetpH shown in the following table:

ENHANCED COAGULATION STEP 2TARGET PH

Alkalinity (mg/L as CaCO3) Target pH

0–60 .......................................... 5.5>60–120 .................................... 6.3>120–240 .................................. 7.0>240 .......................................... 7.5

(iii) For waters with alkalinities ofless than 60 mg/L for which addition ofsmall amounts of alum or equivalentaddition of iron coagulant drives the pHbelow 5.5 before significant TOCremoval occurs, the system must addnecessary chemicals to maintain the pHbetween 5.3 and 5.7 in samples until theTOC removal of 0.3 mg/L per 10 mg/Lalum added (as aluminum) (orequivalant addition of iron coagulant) isreached.

(iv) The system may operate at anycoagulant dose or pH necessary(consistent with other NPDWRs) toachieve the minimum TOC percentremoval approved under paragraph(b)(3) of this section.

(v) If the TOC removal is consistentlyless than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose (asaluminum) at all dosages of alum (orequivalant addition of iron coagulant),the water is deemed to contain TOC notamenable to enhanced coagulation. Thesystem may then apply to the State for

a waiver of enhanced coagulationrequirements.

(c) Compliance calculations. (1)Subpart H systems other than thoseidentified in paragraph (a)(2) or (a)(3) ofthis section must comply withrequirements contained in paragraph(b)(2) of this section. Systems mustcalculate compliance quarterly,beginning after the system has collected12 months of data, by determining anannual average using the followingmethod:

(i) Determine actual monthly TOCpercent removal, equal to:(1—(treated water TOC/source water

TOC)) × 100(ii) Determine the required monthly

TOC percent removal (from either thetable in paragraph (b)(2) of this sectionor from paragraph (b)(3) of this section).

(iii) Divide the value in paragraph(c)(1)(i) of this section by the value inparagraph (c)(1)(ii) of this section.

(iv) Add together the results ofparagraph (c)(1)(iii) of this section forthe last 12 months and divide by 12.

(v) If the value calculated inparagraph (c)(1)(iv) of this section is lessthan 1.00, the system is not incompliance with the TOC percentremoval requirements.

(2) Systems may use the provisions inparagraphs (c)(2)(i) through (v) of thissection in lieu of the calculations inparagraph (c)(1)(i) through (v) of thissection to determine compliance withTOC percent removal requirements.

(i) In any month that the system’streated or source water TOC level,measured according to § 141.131(d)(3),is less than 2.0 mg/L, the system mayassign a monthly value of 1.0 (in lieu ofthe value calculated in paragraph(c)(1)(iii) of this section) whencalculating compliance under theprovisions of paragraph (c)(1) of thissection.

(ii) In any month that a systempracticing softening removes at least 10mg/L of magnesium hardness (asCaCO3), the system may assign a


monthly value of 1.0 (in lieu of thevalue calculated in paragraph (c)(1)(iii)of this section) when calculatingcompliance under the provisions ofparagraph (c)(1) of this section.

(iii) In any month that the system’ssource water SUVA, prior to anytreatment and measured according to§ 141.131(d)(4), is ≤2.0 L/mg-m, thesystem may assign a monthly value of1.0 (in lieu of the value calculated inparagraph (c)(1)(iii) of this section)when calculating compliance under theprovisions of paragraph (c)(1) of thissection.

(iv) In any month that the system’sfinished water SUVA, measuredaccording to § 141.131(d)(4), is ≤2.0 L/mg-m, the system may assign a monthlyvalue of 1.0 (in lieu of the valuecalculated in paragraph (c)(1)(iii) of thissection) when calculating complianceunder the provisions of paragraph (c)(1)of this section.

(v) In any month that a systempracticing enhanced softening lowersalkalinity below 60 mg/L (as CaCO3), thesystem may assign a monthly value of1.0 (in lieu of the value calculated inparagraph (c)(1)(iii) of this section)when calculating compliance under theprovisions of paragraph (c)(1) of thissection.

(3) Subpart H systems usingconventional treatment may alsocomply with the requirements of thissection by meeting the criteria inparagraph (a)(2) or (3) of this section.

(d) Treatment technique requirementsfor DBP precursors. The Administratoridentifies the following as treatmenttechniques to control the level ofdisinfection byproduct precursors indrinking water treatment anddistribution systems: For Subpart Hsystems using conventional treatment,enhanced coagulation or enhancedsoftening.

11. Section 141.154 is amended byadding paragraph (e) to read as follows:

§ 141.154 Required additional healthinformation.

* * * * *(e) Community water systems that

detect TTHM above 0.080 mg/l, butbelow the MCL in § 141.12, as an annualaverage, monitored and calculatedunder the provisions of § 141.30, mustinclude health effects languageprescribed by paragraph (73) ofappendix C to subpart O.

PART 142—NATIONAL PRIMARYDRINKING WATER REGULATIONSIMPLEMENTATION


Authority: 42 U.S.C. 300f, 300g-1, 300g-2300g-3, 300g-4, 300g-5, 300g-6, 300j-4, 300j-9, and 300j-11.

13. Section 142.14 is amended byadding new paragraphs (d)(12), (d)(13),(d)(14), (d)(15), and (d)(16) to read asfollows.

§ 142.14 Records kept by States.

* * * * *(d) * * *(12) Records of the currently

applicable or most recent Statedeterminations, including all supportinginformation and an explanation of thetechnical basis for each decision, madeunder the following provisions of 40CFR part 141, subpart L for the controlof disinfectants and disinfectionbyproducts. These records must alsoinclude interim measures towardinstallation.

(i) States must keep records ofsystems that are installing GAC ormembrane technology in accordancewith § 141.64(b)(2) of this chapter.These records must include the date bywhich the system is required to havecompleted installation.

(ii) States must keep records ofsystems that are required, by the State,to meet alternative minimum TOCremoval requirements or for whom theState has determined that the sourcewater is not amenable to enhancedcoagulation in accordance with§ 141.135(b)(3) and (4) of this chapter,respectively. These records mustinclude the alternative limits andrationale for establishing the alternativelimits.

(iii) States must keep records ofsubpart H systems using conventionaltreatment meeting any of the alternativecompliance criteria in § 141.135(a)(2) or(3) of this chapter.

(iv) States must keep a register ofqualified operators that have met theState requirements developed under§ 142.16(f)(2).

(13) Records of systems with multiplewells considered to be one treatmentplant in accordance with § 141.132(a)(2)of this chapter and § 142.16(f)(5).

(14) Monitoring plans for subpart Hsystems serving more than 3,300persons in accordance with § 141.132(f)of this chapter.

(15) List of laboratories approved foranalyses in accordance with§ 141.131(b) of this chapter.

(16) List of systems required tomonitor for disinfectants anddisinfection byproducts in accordancewith part 141, subpart L of this chapter.The list must indicate whatdisinfectants and DBPs, other than

chlorine, TTHM, and HAA5, if any, aremeasured.* * * * *

14. Section 142.16 is amended byadding paragraph (h) to read as follows.

§ 142.16 Special primacy requirements.* * * * *

(h) Requirements for States to adopt40 CFR part 141, subpart L. In additionto the general primacy requirementselsewhere in this part, including therequirement that State regulations be atleast as stringent as federalrequirements, an application forapproval of a State program revisionthat adopts 40 CFR part 141, subpart L,must contain a description of how theState will accomplish the followingprogram requirements:

(1) Section 141.64(b)(2) of this chapter(interim treatment requirements).Determine any interim treatmentrequirements for those systems electingto install GAC or membrane filtrationand granted additional time to complywith § 141.64 of this chapter.

(2) Section 141.130(c) of this chapter(qualification of operators). Qualifyoperators of public water systemssubject to 40 CFR part 141, subpart L.Qualification requirements establishedfor operators of systems subject to 40CFR part 141, subpart H—Filtration andDisinfection may be used in whole or inpart to establish operator qualificationrequirements for meeting 40 CFR part141, subpart L requirements if the Statedetermines that the 40 CFR part 141,subpart H requirements are appropriateand applicable for meeting subpart Lrequirements.

(3) Section 141.131(c)(2) of thischapter (DPD colorimetric test kits).Approve DPD colorimetric test kits forfree and total chlorine measurements.State approval granted under§ 141.74(a)(2) of this chapter for the useof DPD colorimetric test kits for freechlorine testing is acceptable for the useof DPD test kits in measuring freechlorine residuals as required in 40 CFRpart 141, subpart L.

(4) Sections 141.131(c)(3) and (d) ofthis chapter (State approval of parties toconduct analyses). Approve parties toconduct pH, bromide, alkalinity, andresidual disinfectant concentrationmeasurements. The State’s process forapproving parties performing waterquality measurements for systemssubject to 40 CFR part 141, subpart Hrequirements in paragraph (b)(2)(i)(D) ofthis section may be used for approvingparties measuring water qualityparameters for systems subject tosubpart L requirements, if the Statedetermines the process is appropriateand applicable.


(5) Section 141.132(a)(2) of thischapter (multiple wells as a singlesource). Define the criteria to use todetermine if multiple wells are beingdrawn from a single aquifer and

therefore be considered a single sourcefor compliance with monitoringrequirements.

(6) Approve alternate minimum TOCremoval (Step 2) requirements, as

allowed under the provisions of§ 141.135(b) of this chapter.

[FR Doc. 98–32887 Filed 12–15–98; 8:45 am]BILLING CODE 6560–50–U

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