ANNUAL DRINKING WATER QUALITY REPORT 2020

This Annual Drinking Water Quality Report provides information on the quality of your drinking water. The United States Environmental Protection Agency (EPA) requires all drinking water suppliers to provide their customers with a water quality report on an annual basis. This report contains important information on the source of your water, what it contains, and how it compares to standards set by regulatory agencies.

ANNUAL DRINKING WATER QUALITY REPORT

2020

Dear Waterworks Customers,2020 was a year of reflection on the past and anticipation for the future of Mount Pleasant Waterworks (MPW). After 32 years of waking up each day to lead a team of passionate public servants, I announced my retirement, and the Commissioners launched a national search for the utility’s next general manager.

Allan Clum, our current operations manager, was unanimously selected to take the reins of the organization starting July 1, 2021. A 20-year water industry veteran, Allan has remained an active research chemist. His passion for the science involved in continuously delivering high quality water, combined with a dedication to the future of MPW, will serve the citizens of Mount Pleasant well.

MPW is committed to providing you with a safe, clean, and reliable water supply. It has been the priority of the utility under my leadership and will remain our top priority. Based on the water quality monitoring data collected in 2020, MPW’s drinking water surpassed all state and federal drinking water health standards. These standards for treating, providing, and monitoring drinking water ensure that

our customers always have safe, clean water at their fingertips.

Thank you for your continued support of the men and women at MPW who strive to provide our community with clean water every day.

Sincerely,

Clay Duffie, General Manager

Left to right: Clay Duffie and Allan Clum

Your water comes from the Charleston Aquifer, a pristine groundwater source estimated to be more than 50,000 years old. Six wells are drilled to an average of 2,000 feet below the earth’s surface and groundwater is pumped to four Reverse Osmosis (RO) treatment plants and disinfected with chloramines. To supplement water demand, additional water is purchased under a wholesale contract with Charleston Water System. This supplemental drinking water is sourced from the Bushy Park Reservoir and the Edisto River. The surface water is treated by conventional water treatment and disinfected with chloramines. You can find more details on the surface water source at www.charlestonwater.com/232/Water-Quality-Reports. A complete source water assessment is available upon request.

Where does my water come from?

MPW Service AreaMount Pleasant Waterworks serves more than 90,000 people in the vibrant and thriving Mount Pleasant community. The MPW treatment and distribution system is comprised of approximately 550 miles of conveyance pipe, four RO water treatment plants, six deep wells, eight ground storage tanks, one operational elevated tank, three aquifer storage and recovery (ASR) wells, and two wholesale water intakes.

NORTHMT. PLEASANT

DANIELISLAND

526

17

17

ARTHUR RAVENEL BRIDGE

BEN SAW

YER BLVD.

COLEMAN BLVD.

CHARLESTON HARBOR

ATLANTICOCEAN

MARKET ATOAKLAND

ISLE OF PALMS

MT. PLEASANT

SEWEE RD.

17

41

IOP CONNECTOR

RIFLE RANGE RD.

23

4

1

21

2

LEGENDWater Treatment Plant

Ground Storage

Elevated Storage

Deep Wells

Purchased Surface Water

ASR Wells

Service Area

RO Dispensers

23

1

2

4

3

6

5

1

Reverse Osmosis (RO) water dispensers are located at three RO water treatment plants:

Plant 1 King St. near the corner of Simmons St. (Old Village)

Plant 2 7th Ave. near the corner of Mathis Ferry Rd.

Plant 3 Labor Camp Rd. off Venning Rd.

2020 Annual Drinking Water Quality Report 1www.mountpleasantwaterworks.com

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http://www.charlestonwater.com/232/Water-Quality-Reports

http://www.charlestonwater.com/232/Water-Quality-Reports

Regulated and Unregulated Water Quality Monitoring MPW routinely monitors for constituents in your drinking water according to federal and state laws. Monitoring results for the period of January 1 to December 31, 2020, unless otherwise noted, are included in the following tables. The state allows MPW to monitor for some constituents less than once per year because the concentrations are not expected to vary significantly from year to year, or the system is not considered vulnerable to the constituent. Therefore, some of our data, though representative, may be more than one year old.

MPW’S WATER QUALITY

DRINKING WATER ANALYSIS DATA FOR 2020

PURCHASED SURFACE WATER QUALITY

2 2020 Annual Drinking Water Quality Report www.mountpleasantwaterworks.com

Constituents MCLG or MRDLG

MCL, TT, or MRDL

Highest Level Detected In Your Water

RangeSample

Date Violation Typical SourceLow High Disinfectants & Disinfection By-Products (There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants) Chloramine (as Cl2) (mg/L) 4 4 3 2 3 2020 No Water additive used to control microbes Inorganic Constituents

Fluoride (ppm) 4 4 0.67 0.45 0.67 2020 No Erosion of natural deposits; Water additive which promotes strong teeth

Nitrate [measured as Nitrogen] (ppm) 10 10 0.18 NA NA 2020 No Runoff from fertilizer use; Leaching from septic tanks, sewage; Erosion of natural deposits

Total Organic Carbon

Total Organic Carbon (% Removal) Required removal= 35-50%

TT Average % Removal =61.4% 57% 65% 2020 No Naturally present in the environment

Turbidity Turbidity (NTU) NA 0.3 0.12 NA NA 2020 No Soil runoff 100% of the samples were below the TT value of .3. A value less than 95% constitutes a TT violation. The highest single measurement was .12. Any measurement in excess of 1 is a violation unless otherwise approved by the state. 2020 Unregulated Contaminant Monitoring (UCMR4)

Name Reported Level Range

Sample DateLow High

Manganese (ppb) 9.38 6.15 14.4 2020 EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SDWA).

Bromide (ppm) 0.04 0.03 0.04 2020

Total Organic Carbon (TOC) (ppm) 7.45 6.46 7.98 2020

ConstituentsMCLG or MRDLG

MCL, TT, or MRDL

Highest Level Detected In Your Water

RangeSample

Date Violation Typical SourceLow High Disinfectants & Disinfection By-Products (There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants) Chloramine (as Cl2) (mg/L) 4 4 3 2 3 2020 No Water additive used to control microbes Haloacetic Acids (HAA5) (ppb) NA 60 20.25 ND 20.25 2020 No

By-product of drinking water disinfection TTHMs [Total Trihalomethanes] (ppb) NA 80 15.48 ND 15.48 2020 No Inorganic Constituents Fluoride (ppm) 4 4 0.54 0.14 0.54 2017-2019 No

Erosion of natural deposits Sodium (ppm) MNR NA Average = 46 24 69 2017-2019 NoMicrobiological Constituents

Total Coliform (RTCR) NA TT 2.0 % positive samples. All repeats were negative 0% 2.0% 2020 No Naturally present in the environment

Radioactive Constituents Alpha emitters (pCi/L) 0 15 2.96 ND 2.96 2019 No Erosion of natural deposits

2019 Unregulated Contaminant Monitoring (UCMR4)

Name Reported Level

Range

Sample DateLow High HAA6Br (ug/L) 3.99 ND 3.99 2019 EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) to

collect data for contaminants that are suspected to be present in drinking water and do not have health-based standards set under the Safe Drinking Water Act (SDWA).

HAA9 (ug/L) 10.31 0.318 18.5 2019

Manganese (ug/L) 6.41 0.678 10.4 2019

ConstituentEPA Lifetime

Health Advisory

Highest Level Detected in Your Water

Gen X (ppt) NA 0

Perfluorobutanesulfonic acid (PFBS) (ppt) NA 2.5

Perfluoroheptanoic acid (PFHpA) (ppt) NA 2.1

Perfluorohexanesulfonic acid (PFHxS) (ppt) NA 0

Perfluorononanoic acid (PFNA) (ppt) NA 0

Perfluorohexanoic acid (PFHxA) (ppt) NA 3.6

Perfluorooctanesulfonic acid (PFOS) (ppt) 70 5.7

Perfluorooctanoic acid (PFOA) (ppt) 70 3.0

Voluntary Water Quality Monitoring

Constituent Average in Your Water EPA Secondary MCL

Chloride (ppm) 39 250

Sodium (ppm) 63 NA

Alkalinity (ppm) 110 NA

Hardness (ppm) 48 NA

pH (S.U.) 8.27 NA

GENERAL INTEREST WATER QUALITY

Constituent MCLG ALYour Water

(90th percentile)Sample

Date# Samples

Exceeding AL Exceeds AL Typical Source

Copper - action level at consumer taps (ppm) 1.3 1.3 0.07 2020 0 No Corrosion of household plumbing systems; Erosion of natural deposits

Lead - action level at consumer taps (ppb) 0 15 0.66 2020 0 No

LEAD & COPPER WATER QUALITY MONITORING

For more information please contact: MPW Laboratory at 843-884-9626


GROUNDWATER RULE TRIGGERED MONITORING VIOLATION MPW is required to monitor your drinking water for specific contaminants on a routine basis. Results of routine monitoring are an indicator of whether our drinking water meets health standards. In June 2020, we inadvertently omitted one sample for groundwater source monitoring which resulted in a violation of South Carolina’s groundwater rule. Upon notification, we immediately took the required samples. MPW routinely monitors water quality 24/7 and our records indicate

water quality was not compromised because of the missed sample. Additional samples were taken from this location to confirm our commitment to high-quality drinking water. As our customers, you have a right to know what happened. There were no impacts to public health or safety, and this does not require you to act. For more information, please contact Laboratory Director Jestine Deepe at 843-886-9626.

LEAD IN DRINKING WATER MPW is committed to delivering safe water to our customers. The water we provide to homes and businesses is lead-free, but lead can get into the water as it moves through customer-owned water service lines and household plumbing that contain lead. Service lines bring water into a home or building from MPW’s water main delivery pipe in the street. If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. MPW is responsible for providing high quality drinking water but cannot control the materials used in customer-owned plumbing

components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. If you are concerned about lead in your water, we provide complementary testing. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or at www.epa.gov/safewater/lead. For a complementary lead test please contact our customer service line at 843-884-9626.

EMERGING CONSTITUENTS PFOS/PFOA

http://www.epa.gov/safewater/lead

How are Sources of Water Impacted?The sources for drinking water, both tap and bottled water, include; rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and can pick up substances resulting from the presence of animals or from human activity:

ABBREVIATIONS & DEFINITIONS ug/L: Number of micrograms of substance in one liter of water

ppm: parts per million, or milligrams per liter (mg/L)

ppb: parts per billion, or micrograms per liter (µg/L)

ppt: parts per trillion, or nanograms per liter (ng/L)

mg/L: Number of milligrams of substance in one liter of water

pCi/L: picocuries per liter (a measure of radioactivity)

% positive samples/month: Percent of samples taken monthly that were positive

% removal: Amount of constituent removed in percent

NA: Not Applicable

ND: Not Detected

MNR: Monitoring Not Required, but recommended.

NTU: Nephelometric Turbidity Unit

S.U.: Standard Unit of measurement

MCLG: Maximum Contaminant Level Goal: The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.

MCL: Maximum Contaminant Level: The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology.

TT: Treatment Technique: A required process intended to reduce the level of a contaminant in drinking water.

AL: Action Level: The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.

MRDLG: Maximum Residual Disinfection Level Goal: The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

MRDL: Maximum Residual Disinfectant Level: The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

RTCR: Revised Total Coliform Rule

Microbial Constituents such as viruses and bacteria, that may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

Inorganic Constituents such as salts and metals, which can be naturally occurring or result from urban stormwater runoff, industrial, or domestic wastewater discharges, oil and gas production, mining, or farming.

Pesticides and herbicides which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.

Organic Chemical Constituents including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, and septic systems.

Radioactive Constituents which can be naturally occurring or be the result of oil and gas production and mining activities.

For more information about contaminants and potential health effects call the Environmental Protection Agency’s Safe Drinking Water Hotline at 1-800-426-4791.

4 2020 Annual Drinking Water Quality Report www.mountpleasantwaterworks.com

BUILDING A THIRD WATER CONNECTION

BENEATH THE INTRACOASTALLong-range planning has always been a key element in meeting our customers’ needs. In response to a growing population, MPW partnered with Charleston Water System to connect the two utility’s water systems via a 5,000 linear foot new water main beneath the Intracoastal Waterway. At completion, both utility’s customers will benefit by way of access to an additional water supply, ensuring water demands are met.

How is MPW’s Groundwater Treated?

Withdraw from the Charleston Aquifer (2000 ft below the Earth’s surface)

Prefilter 1.0 micron to remove dirt, sand, rust, grit, and other suspended matter from water.

Reverse Osmosis Membranes A partially permeable membrane which removes pathogens, bacteria, ions, unwanted molecules and larger particles from drinking water.

Corrosion Control Calcium Chloride is added to adjust pH for optimum corrosion control and protect water pipes from leaching heavy metals.

Raw Water Blend 10% of our groundwater source is blended with Reverse Osmosis treated water to naturally add fluoride and other beneficial minerals.

Disinfection Chlorine (sodium hypochlorite) and ammonia gas is added to the water to kill potential harmful organisms before the water leaves the plant. Chloramine maintains the disinfection in the water system.


EPA SPECIAL NOTICE FOR IMMUNO-COMPROMISED PERSONSSome people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised people, such as people with cancer undergoing chemotherapy, people who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly and infants, can be particularly at risk of infections. These people should seek advice about drinking water from their health care providers. Guidelines from the EPA and the Centers for Disease Control and Prevention on appropriate means to lessen the risk of infection by cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline, 1-800-426-4791.

843-884-9626 • [email protected]

1619 Rifle Range Road, Mount Pleasant, SC 29464

WE ALL HAVE SOMETHING AT STAKE WHEN IT COMES TO CLEAN WATER.Our team of water experts provides you with clean, safe, drinking water, 24/7, 365 days-a-year, without missing a beat. We are the unseen, unheard public servants protecting our community and our local environment.

Our continued commitment to our customers and each other is why we continue to be one of the Best Places to Work in South Carolina.

ESSENTIAL WORKERSCommission Meetings3rd Monday of the month5:00 PM

http://[email protected]

ANNUAL DRINKING WATER QUALITY REPORT 2020

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