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Ministry of Energy and WaterGround Floor, Corniche du FleuveBeirut, Lebanon.Website: www.energyandwater.gov.lbTelephone: 01-565100

NATION

AL GUIDELINE FOR RAIN

WATER HARVESTIN

G SYSTEMS


NATIONAL GUIDELINE FOR RAINWATERHARVESTING SYSTEMS

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2016

National guideline Introduction.qxp_Layout 1 2/7/17 3:44 PM Page 01

AuthorMs. Rima Sorour Al-Housseiny

Copyright © UNDP and Ministry of Energy and Water - 2016

Reproduction is authorized provided the source is acknowledged andprovided reproduction is not sold.


TABLE OF CONTENTSIntroduction 04

List of Figures 08

List of Tables 09

List of Abbreviations 10

I. Lebanon, a brief overview 111 Land Topography 122 Climate and Precipitation 133 Population 154 Administration 175 Water demand in Lebanon 186 Water regulations and water quality 19

II Rainwater Harvesting As a viable alternative option for water supply 211 How Best to Use Rainwater in the Lebanese Context 222 Rainwater Harvesting, System Description 233 Rainwater Harvesting Categorization 244 Rainwater Usage Categorization 265 Rainwater Treatment Categorization 276 Different Options for Rainwater Use 297 The Municipality Water Storage Tank 318 Grey Water System 329 Storage Tanks Hygiene 3310 The Case of Two or More Catchment Areas 3311 Plumbing Circuit Configuration 34

III Rainwater Harvesting Design Guide 361 Introduction 372 Applicable Codes, Standards and Guidelines 383 Additional Considerations 384 Design and Installation Guidelines 395 Maintenance 72

Glossary 74

References 78

Annexes 81Annex A Rainfall Data for Lebanese Localities 82Annex B List of Meteorological Stations 109Annex C Potable Water Standards Decree 1039/1999:161 110Annex D Water Demand Categorization 112Annex E Pipe Sizes and Friction Factors 114Annex F First Flush Tank Details 116Annex G Pricing Estimates of System Components 118Annex H The Chemical and Bacteriological Characteristics of Rainwater 121

Case Studies 1231 A Public School 1242 A Multi-Disciplinary Center 1253 A Private School 1264 Residential Building 1275 SOS Village 128


04 National guideline f o r r a i n w a t e rharvesting systems

Fresh water is a very precious and rare resource. Water covers75% of the surface of our planet but only some 2.5% is freshwater and less than 1% is readily accessible for human use,the rest being locked as ice, in biomass or practically out ofreach (ref:1).

Currently it is estimated that the available renewablefreshwater resources in Lebanon for an average rainy yearamount to 4,100 MCM (fig.1) or practically 1000m³/capita/year based on a population of 4.3 millioninhabitants not including non-Lebanese residents. This valuefor water availability is practically equal to the 1,000m³/capita/year water scarcity threshold recognized by UNEP(ref:2).

In other words and contrary to popular belief, Lebanon isapproaching the red zone as far as fresh water resources areconcerned. The mismanagement of the water sectorexacerbates this dire situation which may get worse due totwo main factors namely climate change and populationincrease. The first one may lead to a potential 10-15%decrease in precipitations and an increase of 4-20% inevapotranspiration across Lebanon by 2040 (ref:3), whilepopulation is estimated to increase by 30% over the sameperiod (ref:4), ((not taking into consideration non Lebaneseresidents)). Studies have shown that Lebanon has alreadyexperienced an 8% drop in precipitations in Beirut and Tripoliareas (where rainfall records are available) during the last 30years when compared with earlier periods of the previouscentury (ref:5).

Because of the relatively low availability and bad governanceof its water resources, Lebanon is experiencing extreme watershortages in many regions and is dangerously depleting its

underground water reservoirs up to apoint of no return. Consequently, waterlevels of underground reservoirs aredropping at continuous and alarmingrates in many regions of Lebanon andsea water intrusion is observed in mostof the coastal aquifers.

This situation does not bode well and isnot conducive to a sustainabledevelopment of the country.

The National Guideline for RainwaterHarvesting Systems in Lebanon is part of anational strategy, outlined in a documentthat was published in 2010 entitled the“National Water Sector Strategy”, aimingto improve water governance inLebanon with the ultimate goal ofpreserving our national water resourcesand using them in a way that isconducive to sustainable economicgrowth, to healthy social developmentand flourishing biodiversity.

INTRODUCTION

LEBANONCANNOTPROSPERWITHOUT ASTEADY, SECUREAND SAFESUPPLY OFFRESH WATER


RAINWATERHARVESTING DOESNOT ONLY PROVIDEA SOURCE OFWATER THATINCREASES WATERSUPPLY BUT ALSO ITCAN INVOLVE THEPUBLIC IN WATERMANAGEMENT,MAKING WATERMANAGEMENTEVERYBODY’SBUSINESS.

IT GIVESCONSUMERS ASENSE OF PRIDEANDRESPONSIBILITY

05

The present document offers detailed guidelines, technicaland commercial information on how to size and implementrainwater harvesting systems in rural and urban settingsmainly for domestic applications and external uses asapplied to residential units, schools, hospitals and any otherfacility where domestic uses of water are found.

Rainwater Harvesting ‘RWH’ consists of collectingprecipitations falling on roofs, terraces or any adequatesurface that can catch water with a view of storing it for lateruse as prescribed in this document. It has many social, economicand environmental advantages;

• Rainwater being soft water, pipes scaling and corrosion will bedrastically reduced, the same could be said for heatingequipment like boilers, hot water tanks and solar waterheaters.

• Much less quantities of soap and detergents are neededwith soft water for washing hands and cleaning cloth thusmaking economies and reducing the chemical loading ofwaste water being rejected to nature. Liquid detergentsofteners are not required.

• Blending treated rainwater with municipality water will reducethe hardness of the water without necessitating the use ofsofteners thus sparing the cost of the softener and its operation.

• Users that heavily rely on water trucks will find RWH a blessing,it may simply eliminate the truckloads. Also in the eventualoccurrence of water metering in Lebanon at the consumerpremises, thus introducing the “pay as you consumeprinciple”, rainwater harvesting will definitely reduce thewater bill. Rainwater harvesting may easily cut by half themunicipality water requirements of a household.

• Rainfall being captured at the source instead of flowing, stormwater abatement reduces the possibility of soil erosion andflood risks. This is of particular importance in built up areas



where soil permeability has been practically reduced to nilthus increasing storm water surface flows. Collecting therainwater will reduce the stress on the municipality stormwater network.

• Reduce the load on the water supply network duringsummer time when water use is at its peak and rainfall ispractically nil. This is especially important knowing thatLebanon is increasingly reliant on ground water pumpingwhich gravely impacts water tables levels.

This guideline is intended to be used by all categories ofpeople including those with no technical background. Theinformation is presented in an easily accessible andstraightforward way where hopefully the reader will enjoya stimulating experience to devise and build a rainwaterharvesting system that will provide some water supplyindependence.

The contents are divided into three sections with supportingannexes;

Section 1 is a birds-eye view of the country with a focus oncharacteristics that relate to its hydrology as wellas other water issues.

Section 2 introduces the art and science of rainwaterharvesting starting with a description of thedifferent components of the system as well as anoverall view about the different options andscenarios possible for rainwater use.

Section 3 offers detailed guidelines how to plan, size, price,implement and maintain a rainwater harvestingsystem together with tips how to save water. Theannexes contain useful information as well asnecessary data to perform some of thecalculations presented in this section.

RWH IS AN ACT OF RESPONSIBLECITIZENSHIP

Rainwater harvesting hasbeen practiced in this regionfor thousands of years; as thearcheological finds in Jbeiland Jericho have shown. Nearer to us in space andtime is of course thevernacular architecture of themountain, as well as that ofthe urban environment whererainwater harvesting wasone of its main features.


07

Fig.1 Water Budget of Lebanon in a Glimpse (ref:6)

Evapotranspiration 4,500 MCM

Average Total Rainfall(Including Snowfalls)On Lebanese Territory

8,600 MCM

Gross Renewable WaterResources on National Territory

4,100 MCM

UnexploitableGroundwaterTo sea springs 400 MCM

Unavoidable Surface andGroundwater Flows to

NeighboringCountries 1000 MCM

Average available Renewable WaterResources on National Territory asGroundwater 500 MCM andSurface Streams 2,200 MCM



LIST OF FIGURES

Fig. 1 Water Budget of Lebanon in a GlimpseFig. 2 The Administrative Organization of LebanonFig. 3 Water Demand Fig. 4 Water Demand as a Percentage Fig. 5 General Configuration of a RWH SystemFig. 6 Raw Water Harvesting CategorizationFig. 7 Water Treatment Category 1 Process Diagram - WTCAT1Fig. 8 Water Treatment Category 2 Process Diagram - WTCAT2Fig. 9 Recommended Rainwater Use Decision TreeFig. 10 Grey Water Blending SchematicFig. 11 Typical cube configuration (House1) Fig. 12 Typical L shape Configuration (House 2)Fig. 13 Typical House 1 Virtual RWH Roof ReservoirFig. 14 Typical House 2 Virtual RWH Roof ReservoirFig. 15 Floor DrainFig. 16 Dome Type Roof DrainFig. 17 Tower Type Roof DrainFig. 18 Typical Gutter & Downspout Configuration for a Gabled RoofFig. 19 View of a Rectangular DownspoutFig. 20 Detail of a Common DownspoutFig. 21 Detail of First Flush Tank OperationFig. 22ADetail of Underground First Flush TankFig. 22BDetail of Above Ground First Flush TankFig. 23 Storage TanksFig. 24 Typical Blending Tank ConfigurationFig. 25 Grey Water Blending Schematic ExampleFig. 26 Polyethylene TanksFig. 27 Stainless Steel TankFig. 28 Calming InletFig. 29 Tank OverflowFig. 30 Pressure FiltersFig. 31 Micro FiltersFig. 32 Chlorination dosing pump & Hypochlorite TankFig. 33 1stStage Water Treatment Configuration with Down Stream Carbon FilterFig. 34 2nd Stage Water Treatment Configuration without Carbon FilterFig. 35 Submersible PumpsFig. 36 Duplex Submersible Pit PumpsFig. 37 Horizontal Booster PumpFig. 38 Duplex Booster SetFig. 39 Booster Pump Connection DetailsFig. 40 Underground Reservoir Pipework to Roof Tank in suction lift configurationFig. 40A Reservoir with Float Strainer in Submerged suction configurationFig. 40B Reservoir with Float Strainer in suction lift configurationFig. 40C Reservoir with Float Strainer in Submersible Well Pump configurationFig. 40D Reservoir with Float Strainer in Submersible Pit Pump configurationFig. 41 Booster Set Feeding the Building Network

Typical cubeconfiguration(House1)


09

LIST OF TABLES

Table 1 Average Percentage Distribution of Rainfall on a Monthly Basisfor Lebanon

Table 2 Average Rainfalls for Selected Regions of Lebanon (mm/year)Table 3 Mohafazat Population Growth over year 2030 HorizonTable 4 Population Distribution over the Land Horizon 2030Table 5 Lebanon Population Density as function of AltitudeTable 6 Quality Parameters for Selected Rivers in the Dry SeasonTable 7 Litani River Basin Water QualityTable 8 Water Use CategorizationTable 9 Plumbing Network Configurations with respect to USECAT

OptionsTable 10 De-rating Factor for RWH Catchment SurfacesTable 11 Sizing of Horizontal LeadersTable 12 Sizing of Gutters Table 13 House 1 Domestic Water ConsumptionTable 14 House 1 Irrigation Water Consumption SprinklersTable 15 House 1 Irrigation Water Consumption, Shrubberies / TreesTable 16 Classification of Municipality Water Availability Table 17 Tank Materials EvaluationTable 18 Treatment Techniques



LIST OFABBREVIATIONS

AGT Above Ground Tankcfu/100ml Colony Forming Units per 100 ml literCP Chlorination PumpESMLR Eastern slopes of Mount Lebanon RangeGWB Grey Water BlendingHCT Hypochlorite Chlorination Tankl/m2/d Liter per square meter per dayLMTA Lebanon Mountain Trail Associationl/p/d Liter per person per dayl/shr/d Liter per shrub per dayMCM Million cubic metersm3/capita/year Cubic meters per capita per yearm3/d Cubic meters per daymg/l Milligram per literMWA Municipal Water AvailabilityMWB Municipal Water BlendingPE Polyethylenep/km² Persons per square kilometer PVC Poly-Vinyl ChlorideRWH Rainwater HarvestingRWHCAT Rainwater Harvesting CategoriesRWHS Rainwater Harvesting SystemRWT Rainwater TreatmentS SchemeTDH Total Discharge HeadTDS Total Dissolved SolidsTSS Total Suspended SolidsUGT Under Ground TankUNDP United Nation Development ProgramUNEP United Nation Environment ProgramUSAID United States Agency for International

DevelopmentUSECAT Use categorizationWMM Western Mid-Mountain WSMLR Western Slopes of Mount Lebanon RangeWTCAT Water Treatment Categorization


LEBANON, A BRIEFOVERVIEW

I

1LAND TOPOGRAPHY

2CLIMATE AND PRECIPITATION

3POPULATION

4ADMINISTRATION

5WATER DEMAND IN LEBANON

6WATER REGULATIONS AND WATER QUALITY

The main purpose of this section is to give abrief summary of the characteristics of thecountry directly related to RainwaterHarvesting and water availability thus givingthe reader some background on and anappreciation of the subject being dealt with.


12

Lebanon is located on the Eastern shores of the MediterraneanSea, it has a nominal area of 10,452 km². The country stretches225 km lengthwise along a N-NE / S-SW axis with a widthtapering from 88 km in the North to 35 km in the South. Itslatitudinal span is 33.2 – 34.7 ºN while its longitudinal one is35.2 – 36.6 ºE.

Its topography is made up West to East of a coastal plain andtwo parallel mountain ranges that taper off at both ends,respectively the Lebanon and the Anti-Lebanon separated by aninland plateau, the Bekaa.

The narrow very fertile coastal plain squeezed between theMediterranean Sea and the Western foothills of the LebanonRange has a maximum width not exceeding 6.5 km in the Northinterrupted in few places by the advances of promontoriesplunging abruptly into the sea as at “Nahr el Kalb”.

The Lebanon Range with its highest peak towering above3000 m in the North has a very abrupt and rugged topographycharacterized by valleys and deep clefts running East-Westperpendicular to its dorsal therefore dividing the range intosteep sloped natural bastions that form drainage basins forwaterways and springs. The snow- capped ranges of MountLebanon at altitudes above 1800 m constitute the open airwater reservoirs of the country that feed waterways andunderground aquifers long after the rain has stopped. Howevertill the present time, the exact contribution of the snow coverto the water supply of the country has not been well studied andinvestigated.

The Bekaa Plain, lying at the East of the Lebanon Range is a veryfertile High Land about 16 km wide and 129 km long gentlysloping from an altitude of 1100 to 900 m from North to South.It is crossed lengthwise along its lower stretch by the Litani river,the most important waterway in Lebanon. The Hermel is the

National guideline f o r r a i n w a t e rharvesting systems

LAND TOPOGRAPHY 1

THE SNOW- CAPPEDRANGES OF MOUNTLEBANON AT ALTITUDESABOVE 1800MCONSTITUTE THE OPENAIR WATER RESERVOIRSOF THE COUNTRY THATFEED WATERWAYS ANDUNDERGROUNDAQUIFERS LONG AFTERTHE RAIN HAS STOPPED.

northern stretch of the Bekaa plain, it isitself crossed lengthwise by the Orontesriver, one of two rivers shared withbordering countries, the other being theHasbani.

East of the Bekaa stands the Anti-Lebanon Range which separatesbetween Lebanon and the Syrian inland,its highest peak located southward,Mount Hermon, rises to 2860 m. Unlikethe Lebanon Range, the Anti-Lebanon israther thinly populated and vegetated.The Hasbani, a tributary of the Jordanriver, is the only perennial waterway inLebanon having its sources from theAnti-Lebanon.

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13

Practically speaking, around 85% of theprecipitations in Lebanon are concentratedover 5 month from November to March.This has profound implications on RWHSand especially in what relates to storage.

The littoral and the Western Slopes of MountLebanon Range (WSMLR) havepredominantly a Mediterranean climatewhere up to 500 m altitude, average yearlyprecipitations vary between 800 and1000mm while at higher altitudes up to1800 m average yearly rainfall may reach1400 mm (Dahr el-Baidar, Qartaba).Generally, rainfall increases on the WSMLRat the rate of 25mm for each 100melevation.

There are no precise precipitations data ataltitudes higher than 1800 m because theavailable measuring equipment is notadapted to snowy and cold weatheraccording to the meteorological service at

Beirut airport. However this is of no serious consequence for thepurpose of this document because there is hardly any permanenthuman settlement in Lebanon above 1900 m altitude. Actually thehighest village in Lebanon, Bkaa Kafra in the North, lies between1600 - 1800 m altitudes.

On average, the littoral and the WSMLR, experience between 60and 80 rainy days a year and at altitudes above 1200 m, around halfthat amount of snowy days.

The Eastern slopes of Mount Lebanon Range, the Bekaa plain andthe Anti-Lebanon Range have more of a continental climate beingless exposed to the dampening effect of the Mediterranean. Theaverage yearly rainfall in the Bekaa plain varies in increasingintensity from North to South. It ranges from 450 mm (HaouchSnaid) to 1000 mm (Khorbet Kanafar) while the Hermel area whichlies at the northern extremities of the Bekaa plain experiences arather arid climate with average yearly rainfalls not exceeding250 mm. Baalbeck itself which is the southern gateway to theHermel receives an average of 450 mm. There are no readings for the Anti-Lebanon which receives togetherwith the Hermel area the least amount of rain, however someareas in the Wadi el Taym corridor which lies at the foothills of

Lebanon exhibits diverse micro climateswith varying amounts of precipitations. Ithas a rather long dry season extendingfrom April to October and a shorter wetseason from November to Marchcharacterized by relatively short,

interspersed but heavy downpours. Overall, on an average rainyyear, Lebanon receives some 800 mm of rainfall.

Rainfall monthly percentage distribution is practically the sameall over Lebanon (Table 1) despite variations in quantitiesdepending on regions (Table 2).

CLIMATE AND PRECIPITATION 2

Table 1. Average Percentage Distribution Of Rainfall On A Monthly Basis For Lebanon – (Ref:22)

Source: Meteorological data of Lebanon

SEP0.7%

OCT6.8%

NOV11.8%

DEC19.9%

JAN22.4%

FEB17.1%

MAR12.9%

APR6.4%

MAY1.6%

JUN0.3%

JUL0.1%

AUG0.1%


14

On average, rainfall events in Lebanon rarelyexceed 10days, the weighted average beingaround 1.5 days. Moreover rainfall eventexceeding 4 days rarely occur more thanonce a year. Basically, heavy rainfall events inLebanon are characterized by their brevityand intensity which is typical of aMediterranean climate. It is not uncommonfor daily rainfalls to reach 200 mm at midaltitudes or 100mm at the littoral.

On average, one rainy day out of 10 receivesmore than 30mm of rainfall in the coastalregion and 45 mm at mid altitudes, whilearound half of the rainy days on the nationalterritory yield less than 5mm.Overall heavyrainy days that yield rainfalls in excess of40 mm do not exceed 20% of rainy daysover any one year.

Rainfall recording started in Lebanon some137 years ago at the meteorologicalobservatory of the American University ofBeirut. Since then many stations wereadded over the years to cover most areas ofLebanon and some even in Syria. By 1975some 146 stations were more or lessoperational but this number quicklydiminishedat the onset of instability duringthat year. Practically only three stations keptoperating namely Beirut airport, Ksara in theBekaa and Tripoli. Thus only these stationshave complete recording series that extendover relatively long periods of time.

Starting in the 1990s, some more existingstations were recording again and newstations were put into service, currently 39stations are operational with more beingplanned. The stations listing are as shownin Annex B.

the Anti-Lebanon at the level of the southern Bekaa plain stillreceive some 1000 mm of rainfall (Hasbaya, Kfair ez-zayt).

Table 2. Average Rainfalls For Selected Regions Of Lebanon – (Ref:22)


Predominant winds in Lebanon blow in a West/South-Westdirection for most of the year, Easterlies and Northern winds are oflesser occurrence but of significant effect especially Easterlies thatbring sandstorms from the Syrian inland and Arabian peninsuladuring spring and less frequently in summer and autumn.

The winds do have an impact on RWHS as far as rainfall waterquality is concerned as shown further below.

Precipitations in Lebanon could have drastic annual variability; insome regions inter-annual variability may exceed 500% betweenexceptionally rainy and dry years. The year 2014 is a good exampleof a dry year where average precipitations on the national soil werenearly half the annual average knowing that this year is not theworst that Lebanon has experienced or will probably experience inthe future.

Source: Meteorological data of Lebanon

RegionBeirutLittoral North up to 500 m altitudeLittoral Center up to 500 m altitudeLittoral South up to 500 m altitudeWSMLR 500 – 1200 mWSMLR 1200 – 1800 mBekaa North Bekaa CenterBekaa SouthLitani basinOrontes basinYammouneh HermelWadi el Taym

Rainfall (mm/year)710745850655120011004506908707184501000250917

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15

However, the age pyramid of Lebanon isstarting to thin out at the bottom a clearindication of demographic maturity andlower future population growth rates(ref:7).

Residents in Lebanon are expected to top 5 million by 2030(Table 3) with an expected average yearly growth rate of 1 %(ref:4). The most economically developed areas of Lebanonnamely Beirut and Mount Lebanon are heavily urbanized while theperiphery which is sill to a certain extent rural is less so (Table 4).

countries in the world if small entities like the Vatican state andHonk Kong are not taken into consideration. If non-nationalresidents are taken into account, it is one of the five mostpopulated countries in the world.

With a current population of some4,200,000 inhabitants yielding anoccupancy density of around 400p/km²,Lebanon is one of the ten most populated

POPULATION3

MOHAFAZAT Beirut & Mount LebanonNorth Lebanon & AkkarSouth Lebanon & NabatyehBekaa & Baalbeck-HermelTOTAL

20001,910,896807,204747,477539,4484,005,025

20302,310,0001,140,0001,040,000740,0005,230,000

Table 3. Mohafazat Population Growth Over Year 2030 Horizon (Ref:4)

Source: NPMPLT, 2005, chapter 2, Table 4

TOTALPOPULATION1,910,896807,204747,477539,4484,005,025

POPULATIONIN URBANCENTERS1,651,000385,000327,000181,0002,544,000

86%48%44%34%64%

TOTALPOPULATION2,310,0001,140,0001,040,000740,0005,230,000

POPULATIONIN URBANCENTERS1,990,000620,000490,000300,0003,400,000

86%54%48%40%65%

Table 4. Population Distribution Over The Land Horizon 2030 (Ref:4)

Source: NPMPLT, 2005, chapter 2, Table 6

% Growth21.2241.1837.9338.9030.79

YEAR 2000 YEAR 2030

MOHAFAZAT

Beirut & Mount LebanonNorth Lebanon & AkkarSouth Lebanon & NabatyehBekaa & Baalbeck-HermelTOTAL


16

80% of the residents live on the coastal zone (0-400 m)making out of it one of the most densely populatedareas in the world (1310 p/km²) as shown in (Table 5).


However with the huge influx of people to Lebanonfleeing conflict areas in neighboring Syria mostdemographic statistics of Lebanon are currentlyoutdated thus requiring major revisions.

It is estimated that the current resident population inLebanon is around 5.5 million and while this numbermay increase in the near future depending on thesituation in the area, it might not drop down any timesoon thus putting increased pressure on waterdemand.

The effect on water demand caused by the alarmingincrease in population is even further magnified by thehigher living standards sought out by the population asa direct outcome of economic growth and socialawareness.

Currently, the average household size in Lebanon isestimated at 4.3 persons, living in around 1 milliondwelling units.

ALTITUDE RANGE(m)

0 – 400

400 – 800

800 – 1200

1200 – 1600

1600 – 2000

> 2000

POPULATION DENSITY(P/Km²)

1,310

278

257

91

15

1

CLIMATE ZONE

Coastal (Zone 1)

Coastal (Zone 1)

WMM (Zone 2) & In-land Plateau (Zone 3)

WMM (Zone 2) up to 1400 m

High Mountain (Zone 4)

High Mountain (Zone 4)

CURRENTLY, THEAVERAGE HOUSEHOLDSIZE IN LEBANON ISESTIMATED AT 4.3PERSONS, LIVING INAROUND 1 MILLIONDWELLING UNITS.

Table 5. Lebanon Population Density As Function Of Altitude (Ref:4)

Source: NPMPLT, 2005, (column 3 added), WMM: Western Mid-Mountain


17

Lebanon is divided into 6 governorates(Mohafazat) namely, North Lebanon,Bekaa, Mount Lebanon, Beirut, Nabatyehand South Lebanon, divided into a total of25 districts (caza) themselves composedof municipalities. Beirut has no districtsbut has a municipality.

With the exception of Beirut, theMohafazats and their caza extend overseveral climatic zones thus experiencingdifferent rainfall regimes. Hence, withthe exception of Beirut, any oneMohafazat or even caza cannot becharacterized by one average rainfallnumber for the purposes of thisguidebook if a minimum of accuracy inthe calculations is to be ensured.Consequently rainfall data will bepresented at the town and village level.

This is possible because all themeteorological stations in Lebanon arelocated in or nearby towns and villages,as for agglomerations that are far away,geographical characteristics similar toareas where the meteorological stationsare located will be used as proxy. Basicallythe two parameters that govern suchsimilarity are altitude and topographicallocations. Thus for example two villagesrelatively far apart but having nearlysimilar altitudes and topographicallocations (located on the western side ofmount Lebanon range) will experienceroughly the same amount of rain fall.

ADMINISTRATION 4

Fig.2 The Administrative Organization of Lebanon



Agriculture is the largest water consumer; it absorbs some55% of the water supply. This share is expected to rise to60% by 2030 (ref:14). The domestic water supply wasestimated at 505 MCM for 2010, it is roughly distributedas follows over the different Mohafazat;

WATER DEMAND IN LEBANON5

WATER DEMAND INLEBANON IS EXPECTEDTO INCREASE BY 250MCM OVER THE NEXT 20YEARS WITH IRRIGATIONABSORBING MOST OFTHIS INCREASE

It is worthwhile noting that population density and a weakregulatory environment is resulting in serious pollution towater resources which could be considered a form ofhidden demand. Actually water supplies that have beenpolluted could be considered as used water even thoughthey were never physically touched or used byconsumers. This is the basic assumption of the waterfootprint concept.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2010 2015 2020 2025 2030 2035

Domestic Industrial Tourism Irrigation

MCM

by 250 MCM over t

0%

20%

40%

60%

80%

100%

120%

2010 2015 2020 2025 2030 2035

Domestic Industrial Tourism Irrigation

by 250 MCM over t

Fig.3 Water Demand (ref:14) Fig.4 Water Demand as a percentage (ref:14)


19

There are no standards or regulations in Lebanon concerningrainwater harvesting and the use of rainwater. Consequently,the present guideline document has the objective to set clearrequirements regarding the collection, storage, treatment anduse of harvested rainwater.

Most of Lebanon’s waterways are polluted because ofuncontrolled sewage, industrial waste dumping and irrigationwater leaching. The most flagrant example is probably the LitaniRiver and Qaraoun Lake which exhibit alarming levels of all sortsof pollution. Tables 6 & 7 give an idea of the extent of pollutionin some of the waterways (ref:14).

The regulatory framework regardingwater is quite weak in Lebanon. Decree1039 of 2/8/1999 (ref:18) sets qualityrequirements regarding the physical,chemical and bacteriological propertiesfor tap water (potable/drinking waternot bottled water). These requirementsare shown in Annex C of this guideline.(Decree 1039 needs updating…).

WATER REGULATIONS ANDWATER QUALITY

6

NO3(mg/L)

3

2.8

3.4

1

3

3

7

5.5

50

TDS(mg/L)

270

225

280

150

300

200

210

250

600

SO3(mg/L)

20

28

22

8

30

38

22

21

250

TotalColiform(c/100mL)

900

610

26,500

3,500

28,000

490

710

80

500

E. Coli(c/100mL)

20

17

3,000

200

6,000

15

1

0

100

River

Kabir

Bared

Abou Ali

Ibrahim

Antelias

Damour

Awali

Qasmieh

Limit Value

BOD5(mg/L)

14.4

28.2

39.3

62.8

53.2

21.3

33.4

22.5

Nil

Table 6. Quality Parameters For Selected Rivers In The Dry Season (Ref:14)

Source: STLE, 2010, Table 3.11



elevations (e.g., Ain Bahr in Qehmez,Mount Lebanon, 1604m), an indicationthat the pollution is also occurring at higherelevations most probably due to septictanks and discharge into open wells.

Furthermore, over pumping ground wellsin coastal areas has dangerouslyincreased their salinity level.

Under a USAID-funded water awareness program, the LebanonMountain Trail Association (LMTA) in 2013 analyzed 53 springslocated on the LMT, out of 72 springs on the trail. The sampleswere tested at the North Lebanon WWE lab in Tripoli and theIndustrial Research Institute in Hadath. The results showed that38% of the springs have no bacteriologically contamination, 30%have low to moderate contamination, 15% have moderate tohigh contamination, and 17% are highly contaminated. Someof the highly contaminated springs are located at higher

706

7.68

624

62

197

1,500,00

NA

196

7.5

4

62

0.35

450

NA

187

7.27

2.50

0.10

0

1

0.005

221

8.2

2.0

0.8

0

0

0.0007

502

7.93

547

1.23

8.58

71.61

0.01

235

8.27

2.65

0.93

0.09

160

0.01

1979

8.66

1530

4.90

72

400

0.079

256

8.32

3.30

1.2

0.24

400

0.021

<500

6.5-8.5

NA

45

NA

0

<500

6.5-8.5

NA

45

NA

0

<500

6.5-8.5

NA

<10

NA

0

<0.005

<500

6.5-8.5

NA

<10

NA

0

<0.005

Table 7. Litani River Basin Water Quality (Ref:14)

Source: STLE, 2010, Table 3.14

TDS (mg/l)

pH (pH units)

BOD (mg/l)

Nitrates (mg/l as N)

Phosphates(mg/l)

Fecal Coliform(CFU/100ml)

Cadmium (mg/l)

TDS (mg/l)

pH (pH units)

BOD (mg/l)

Nitrates (mg/l as N)

Phosphates(mg/l)

Fecal Coliform(CFU/100ml)

Cadmium (mg/l)

Indicator BAMAS 2005 (Summer) LRBMS 2010 (summer)Drinking Water

Standard

88

6.57

2

3

0

0

NA

120

6.5

<2

16

0.01

0

NA

290.96

7.09

48.46

13.46

11.75

223,487

NA

160

7

2.57

21

0.13

17

NA

MaxMin Mean MaxMin Mean EPALibnor

Lake Water

Surface Waters


RAINWATERHARVESTINGAS A VIABLEALTERNATIVEOPTION FORWATER SUPPLY

II1HOW BEST TO USE RAINWATER IN THELEBANESE CONTEXT

2RAINWATER HARVESTING, SYSTEMDESCRIPTION

3RAINWATER HARVESTINGCATEGORIZATION

4RAINWATER USAGE CATEGORIZATION

5RAINWATER TREATMENT CATEGORIZATION

6DIFFERENT OPTIONS FOR RAINWATER USE

7THE MUNICIPALITY WATER STORAGE TANK

8GREY WATER SYSTEM

9STORAGE TANKS HYGIENE

10THE CASE OF TWO OR MORE CATCHMENT AREAS

11PLUMBING CIRCUIT CONFIGURATION

Rainwater harvesting as scoped in thisdocument is the capture and storage ofrainwater for different purposes includingdomestic use for drinking, bathing, clothwashing, toilet flushing, housekeeping as wellas external uses like landscaping irrigation,surface cleaning, hosing and car washing. Thisguideline is concerned with applicationsmainly focused on residential units, schools,hospitals, hotels and other facilities where theabove mentioned purposes are practiced. It isnot meant to deal with large scale irrigationschemes or industrial processes.

This guide book is addressed to all peopleinterested in implementing a RWH system forthe targeted applications described above.Consequently, the information is presented ina simple straightforward way that is easy tograsp and implement. The guidebook could beused for implementing rainwater harvestingsystems for new projects or as retro-fits forexisting projects.

The present section deals in some details withthe concepts behind RWH as proposed in thisguideline while the next one offersmethodologies how to size, price, implement,operate and maintain a RHW system.



Harvesting rainwater for use during the rainy season isnot very advantageous for users connected to themunicipality water supply. Usually in winter,municipality water is in abundant supply, it is in summerthat water is scarce and has the most economic value.Therefore it is normal to store the rainwater for the leandays. However for users not connected to themunicipality network, rainwater supply could be usedalso during the rainy season which could reduce thestorage tank size but this option reduces the strategicwater storage during the dry period.

Consequently, this guideline not only recommends theuse of relatively large rainwater storage tanks to caterfor the dry season water requirements but also the useof separate municipality water storage tanks but oflesser storage capacity as will be shown in the sectionthat follows.

Municipality water should not normally feed therainwater storage tank, the two systems should be keptseparate. It is very important to follow these guidelinesto make sure rainwater does not back feed into themunicipality water network. This situation mayrepresent a health hazard to all the communityconnected to the municipality network.

HOW BEST TO USE RAINWATER INTHE LEBANESE CONTEXT

1

FOR OPTIMUM WATERRESOURCES USE ASWELL AS FOR SAFETYREASONS, IT ISIMPORTANT TO PROVIDEA MUNICIPALITY WATERSTORAGE TANK. THISTANK WILL ACT AS APHYSICAL SEPARATIONBETWEEN THEMUNICIPALITY WATERFEED NETWORK ANDTHE RAINWATERSYSTEM.


23

• Storage Tank: Also called cistern wherecollected rainwater is stored for future usage.The tank could be located above ground orunderground. The tank could be of concrete,plastic or fiberglass. If rainwater quality is anissue for the intended purpose, additionalcomponents could be introduced, namely:

• First Flush tank: The purpose of this tank is toget rid of the first rainwater for each rain fallevent to avoid channeling debris, mud,contaminated particles and other pollutionto the rainwater storage tank. As the nameimplies, the purpose of this tank is to flush thecatchment surface before collecting waterfor storage. Its main advantage apart fromimproving rainwater quality is to avoid thehassle of manually diverting the collectedrainwater to the drain at least at thebeginning of the rainy season. Howeverbecause Lebanon climate is characterized byrain events that are separated by a relativelylong stretch of non-rainy days during whichthe collection surfaces may be subjected topollution vectors, flushing the first rainwaterat each rain fall event is a necessity for higherquality rainwater.

• Water Treatment: Its purpose is to improvethe quality of the rainwater to expand therange of its use namely for domesticpurposes. Water treatment usually includesmedia and micro-filters, carbon filters,sterilization and domestic water storagetanks. The extent of the water treatmentdepends upon the end use of the collectedrainwater as shown further below.

Rainwater harvesting systems comprise three basic componentsnamely:

• Catchment Surface: It is the collection surface from whichrainfall runs off, it could be the roof of a building, a terrace, aparking pergola roof, a driveway or any area suitable forrainwater collection. The location, construction and exposureof the catchment surface to polluting vectors have a decisiveinfluence on the quality of the rainwater being collected.Hence the less exposed a catchment surface is to atmosphericpollution, human access and use, the lower is the probabilityof serious pollution being entrained by the rainwater run-off.Thus a roof in a rural area that is not normally accessed willmost probably have fewer pollutants than a terrace near anindustrial zone or one that is continuously used.

• Drain system: Run off water collectors (Drains / gutters) andconveying conduits from catchment area to the storage tank.They could be made of metal or plastic as will be explained inthe next section.

Understanding how the fundamental components of arainwater system work is crucial when contemplating designingor installing a RWH system.

RAINWATER HARVESTING,SYSTEM DESCRIPTION

2

RWH Tank

Water Treatment

Domestic Water Tank

Gutter/drain

Leader/downspout

First Flush To use

Catchment Surface

Fig.5 General Configuration of a RWH System


Rainwater harvesting categorization helps expand as much as possiblethe safe use of rainwater in the Lebanese context. This is so for threemain reasons;

1. There are no existing regulations in Lebanon regarding the safecollection and use of rainwater.

2. The consumer has largely no control over rain fall quality.3. The intent of this document is to maximize the collection and use of

rainwater in a safe and rational way, thus to offer the most optionsand scenarios for rainwater harvesting and the subsequent use ofthe collected water.

Furthermore the categorization helps consumer acquire a heightenedawareness and a more informed approach concerning the safecollection and use of rainwater.

For the purpose of this guideline, four Rainwater Harvesting CATegories(RWHCAT) are defined ranging from highest quality RWHCAT1 tolowest quality RWHCAT4;

1- RWHCAT1 complies with the following minimum requirements: • Facility is above 500 m altitude if located in Mount Lebanon

Mohafaza.• Facility is at least 3 km away from any industrial plant that has

smokestacks and 1,500 m away from a hospital that incineratesits medical waste.

• Facility is located in a village or an area that is sparsely populated. • Lowest point of collection surface is at least 3 m above ground

level. • Collection area is not accessible for continuous human

circulation, occupancy or use for solar water heating,photovoltaic, ventilation fans, AC condensing units or any sort ofequipment and planters.

• Collection area has no exhaust outlets like kitchen exhaust,chimney outlet, boiler outlet, etc. that are at less than 2 m heightfrom collection surface.

• There are no overhanging trees aboveCollection surface.

• Trees having a crown above thecollection surface should be at least3 meters away.

• Collection surface and drainageequipment are not made of asbestos,copper, lead or zinc.

• Collection surface is not used forplantations of any kind and has nosoil layer.

• Rainwater storage tank should havefood grade interior finish. Forplastic or fiberglass tanks, foodgrade labeling should be specifiedby the tank manufacturer, for builton site concrete tanks, food gradeis determined by the type ofsurface coating which should bespecified food grade by the coatingmanufacturer.

• Rainwater harvesting system has a firstflush tank in good working order.

2- RWHCAT2 complies with the followingminimum requirements: • Collection area is not accessible for

continuous human circulation,occupancy or use however equipmentthat is not filled with liquids (i.e: fansand photovoltaics) or filled only withwater without additives (i.e: vacuumtubes solar collectors without anti-freeze) are tolerated.

• Collection surfaces and drainageequipment are not made of asbestos.


RAINWATER HARVESTINGCATEGORIZATION

3


25

Fig.6 Raw Water Harvesting Categorization

Some RWHCAT1 requirementsA > 3mB > 2mD > 3m if C > A

In this sketch, the roofis the only catchmentarea that couldpotentially meetRWHCAT1requirements

The terraces couldpotentially complywith RWHCAT3requirements

This area has planters, it does notcomply with any of the fourcategories, and it cannot be usedfor the purpose of RWH.

This area could potentially comply withRWHCAT2 if not readily accessible and incase any equipment installed contains onlywater without additives or no water at all

This area is used as adriveway; it couldpotentially complywith RWHCAT4 if ithas no soil cover orplanters

In this guideline rainwater that drains from plantedareas cannot be used in rainwater harvestingapplications.

• Collection surface is not used forplantations of any kind and has no soil layer.

• Rainwater harvesting system has a firstflush tank in good working order.

3-RWHCAT3 complies with the followingminimum requirements: • Collection surface is not used as a driveway.• Collection surface is not used for

plantations of any kind and has no soil layer.• Rainwater harvesting system has a first

flush tank in good working order.

4-RWHCAT4 complies with the followingminimum requirements:• Collection surface is not used for

plantations of any kind and has no soil layer.

RAINWATER HARVESTINGCATEGORIZATION HELPS EXPANDAS MUCH AS POSSIBLE THE SAFEUSE OF RAINWATER IN THELEBANESE CONTEXT.

IMPORTANT


26

USECAT4. Of course the higher usagecategory could be used for the lowerapplication, but obviously this implies amisallocation of resources.


Rainwater use categorization is a function of rainwater qualityand treatment process, there are four USE CATegories (USECAT)defining the scope of rainwater usage on the consumerpremises; They range from the highest USECAT1 to the lowest

RAINWATER USECATEGORIZATION

4

USE CATEGORY

USECAT1

USECAT2

USECAT3

USECAT4

RECOMMENDED RAINWATER USE

Drinking, cooking (see note below)

Suitable for human contact except drinking and cooking(i.e: bathing, hand wash, housekeeping, laundry, sprinklerirrigation, car wash, hosing, surface cleaning)

Preferably no human contact,(i.e: Toilet flushing, laundry, drip irrigation)

Not suitable for human contact (i.e: Toilet flushing, sub-surface irrigation)

Table 8. Water Use Categorization

DECIDING ON THE USE OF THECOLLECTED RAINWATER IS THE MOSTIMPORTANT FACTOR IN PLANNING ARAINWATER HARVESTING SYSTEM

ALL OTHER CONSIDERATIONSINCLUDING RWH SYSTEMCONFIGURATION DEPEND ON IT

USECAT1 is not applicable tohospitals, schools, hotels and otherlarge facilities because RWHCAT1which is a pre-requisite to USECAT1 ispractically impossible for hospitals,hotels and most other public or officebuildings while for schools and otherlarge facilities, it may not beguaranteed that water quality is beingconstantly monitored as per USECAT1requirements. Therefore USECAT1 is limited toresidential applications.

IMPORTANT NOTE


27

The categorization of the rainwatertreatment is a function of RWHCAT andUSECAT as explained in the next section.

Two Water Treatment CATegories(WTCAT) are proposed in this guideline,namely WTCAT1 and WTCAT2.

WTCAT1 as (fig.7) below shows consistsof a pre-treatment, a first stage treatmentfollowed by a second stage treatment.

RAINWATER TREATMENTCATEGORIZATION

5

The pre-treatment stage consists of straining in the First flushtank then settling in the storage tank. The first stage treatmentconsists of Chlorination, media filtration then micro-filtration,the carbon filter may follow the first treatment stage but is notpart of this stage. The product water is stored in a domestic watertank. The second stage consists of micro filtration, followed by acarbon filter if it was not installed downstream of the first stagethen UV sterilization. The product water is stored in a potablewater stainless steel storage tank. This water treatmentcategory implies also the monthly testing of the potable waterat the potable water tap for bacteriological contamination.

HCT

Micro Filter

DomesticWater Tank

Micro Filter

First Flush

RWHTank

Pre Treatment Treatment 1 Treatment 2

Carbon Filter (Alternative 2 Location)

Carbon Filter (Alternative 1 Location)

Media Filter

PotableWater

Tank

To UseDomestic Water

To Use Potable Water

CP

UV Polishing

Fig.7 Water Treatment Category 1 Process Diagram - WTCAT1



DomesticWater Tank

RWHTank

Pre Treatment Treatment 1

Micro Filter

Media Filter

HCTCP

To Use

First Flush

Fig.8 Water Treatment Category 2 Process Diagram -WTCAT2

WTCAT2 as (fig.8) below, consists of a pre-treatment and a firststage treatment. The pre-treatment stage consists of straining inthe First flush tank then settling in the storage tank. The first stagetreatment consists of Chlorination, media filtration then micro-filtration. The product water is stored in a domestic water tank. Thisguideline does not recommend a carbon filter for this applicationbecause for non-potable domestic water use, residual chlorine doesno harm in the event some is still present in the water at the tap.

WITHIN THE SCOPE OF THISGUIDELINE, WATER TREATMENT ISNOT A LUXURY NOR IS IT ANOPTIONAL ITEM THAT COULD BEOVERLOOKED, IT IS A NECESSITY FORTHE SAFE USE OF RAINWATER

Kindly refer to Annex H to find out more about rainwaterquality.


29

The schematic below shows sevendifferent schemes S1 to S7 that offerpreferred combinations between RWHand RWT methods in view of a

DIFFERENT OPTIONS FORRAINWATER USE

6

RWHCAT1

RWHCAT2

RWHCAT3

USECAT1

WTCAT2 USECAT2

WTCAT2 USECAT2

USECAT3

USECAT3

MWB

USECAT3

RWHCAT4 USECAT4

MWB/GWB

S1

S2

S3

S4

S5

S6

S7

MWB

MWB

MWB

WTCAT1

MWB

Fig.9 Recommended Rainwater Use Decision Tree

contemplated water use. The schemes represent minimumacceptable constructions to achieve water quality for a givenuse; it is always advisable to devise rainwater schemes that aremore stringent than what is proposed below.


30

Even though not shown in the figure above, USECAT4 isapplicable to RWHCAT1, 2 and 3 without any treatment, but itis not a recommended application from a resources allocationview point.

The reader will note that strategies S1 to S6 propose theoptional use of Municipal Water Blending (MWB) while S7shows the option of using Municipal water or Grey WaterBlending (GWB), all with the aim of optimizing waterresources use.

In S1, S2, S4 and S5 blending is done in a blending tankupstream of the treatment 1 stage while in S3 and S6 blendingis done in a blending tank before water use. Dotted arrows inabove combinations represent optional additions in theprocess that are not necessary to reach the sought after waterquality using the proposed combination of RWH and RWT ina given scenario (See Chapter 3 for more details).

Blending has major advantages as follows:

1. It requires the storage of municipal water during the rainyseason, (See next section)

2. It extends as much as possible the use of the rainwater stock3. It is a natural and economic way to soften municipal or wellwater which is relatively hard in Lebanon. The TDS ofmunicipal water is above 650 ppm in most regions ofLebanon and actually could be sensibly higher. Blending50% rainwater 50% municipal water will cut the TDSpractically by two and thus drastically decrease the hardnessof the water without using a softener.

Actually in WTCAT1 and 2 softening is out of the questionbecause rainwater even in the storage tank is still a relativelydistilled water.

Detailed explanations on water treatment will be provided insection 3 below where system design will be tackled.


THE READER WILLNOTE THATSTRATEGIES S1 TOS6 PROPOSE THEOPTIONAL USE OFMUNICIPAL WATERBLENDING (MWB)WHILE S7 SHOWSTHE OPTION OFUSING MUNICIPALWATER OR GREYWATER BLENDING(GWB), ALL WITH THEAIM OF OPTIMIZINGWATER RESOURCESUSE.


31

THE MUNICIPALITY WATERSTORAGE TANK

7

Large storage tanks for municipality waterare a common occurrence for all types ofbuildings in Lebanon. One of the mainreasons for such practice is the fact thatutility water is not in continuous supply,actually in some regions of the country it isnot uncommon for the municipality waterto be cut off for several days in a row oreven for weeks during the dry seasonespecially in low rain years.

If blending is contemplated thenmunicipality water storage tanks are anecessity. Because of water scarcity inLebanon, such a tank has a similar functionto the rainwater storage tank, but itharvests municipality water instead ofrainwater. The idea is that from Decemberto June municipality water is in good supplyin most regions of the country, thereforethe storage tank could be filled over fewweeks while at the same time catering forthe facility day to day use thus storingwater for the dry season.

During the dry season, blending watercould be drawn from the municipalitywater tank on a daily basis in conjunction

with the rainwater use. As a rule of thumb, the municipality tankvolume should be between 30 – 50% of the rainwater storagetank volume depending on the severity of municipal water cutsduring the dry season and the coverage period provided by therainwater storage capacity. More on this will be covered inChapter 3. Municipality water tanks offer strategic water storageespecially during the period from August to October whenmunicipality water or even truck water supply is at its lowest.

IMPORTANTOne major advantage of blending equally rainwater withmunicipality water is the possibility to enjoy a supply of softdomestic water for an extended period without the use ofsofteners thus improving quality of life in the facility atminimum cost in case rainwater is in limited quantities butanyway is being contemplated as a source of water supplyfor the building.

Another strong point is that blending saves on the waterstorage volume in case of equal quantities blending becausethe municipality water tank is usually replenished with waterthough at a slow rate during the dry season. The approach of this guideline is to completely disconnectbetween the municipality water supply and the rainwatersystem upstream of the blending tank. Thus it is notrecommended to provide the rainwater storage tank witha municipality water supply line.



be designed to prevent backflow of GWTinto RWHT. Effluent grey water blending is done inorder to improve the quality of the greywater as far as hardness and alkalinity areconcerned. This will greatly help to preventclogging of the grey water supply pipes,valves and irrigation devices orifices.

Grey water is the effluent from lavatories, showers and bathtubsonly. WC, Laundry machines, Dish washers, kitchen sink and otherplumbing fixtures must not be part of the grey water network.

In a grey water system, these three types of fixtures areconnected to a separate grey water drainage network that feedsinto a grey water treatment scheme made up mainly of asettling/skimming tank, an aeration tank with chlorination, a200 – 300 micron pressure filter and an effluent grey water tankwhich acts also as a blending tank.

In this guideline, Grey water systems are allowed only for blendingwith rainwater in USECAT4 applications. In this case rainwaterfrom the RWH storage tank (RWHT) is conveyed to the effluentgrey water tank (GWT) which acts also as a blending tank. Theeffluent grey water tank should be located in the grey watertreatment plant. In no case it is allowed to pump the effluent greywater to a blending tank in the mechanical room where watertreatment or water storage equipment is located. System should

GREY WATER SYSTEM8

Fig.10 Grey water blending schematic

TP: Transfer PumpBP: Booster Pump

BP

TP

From Catchment Surface

GWTFrom grey watertreatment plant

RWHT

To USECAT4 network

Treated Grey water should not beconveyed to any part of the facilityother than the point of use. In thecase of blending, rainwater from theRWH tank should be conveyed to theeffluent grey water tank. It is notrecommended to have a grey waterblending tank in the mechanicalroom where water treatmentequipment is located.

IMPORTANT


33

If the facility has two or more potentialcatchment areas of different RWHCAT, it ispreferable to have a storage tank for eacharea in order to avoid mixing higher qualityrainwater with lower quality one. Indeed, ifrainwater from a RWHCAT1 catchmentsurface is mixed with rainwater from a

RWHCAT3 catchment surface the mix will be considered aRWHCAT3, thus losing the advantages of the higher quality water.

However by judicious combinations, the two tanks could beused for common applications, for example a RWHCAT1 tankcould feed in common with a RWHCAT2 tank the domesticplumbing system.

STORAGE TANKS HYGIENE9

THE CASE OF TWO OR MORECATCHMENT AREAS

10

Rainwater or municipality water can bestored for several months withoutdegradation in quality provided thestorage tank does not allow sun light andthe water is aerated. The issue of sun lightis relatively simple to address, a concretetank or plastic tank of opaque surfaces

will do the job. Aeration is another issue, it is mostrecommended to equip tanks higher than 50 m² capacity ortanks where water will be stored for more than 2 month, with arecirculation line. This system uses the storage tank pumpwhich operates for a limited time daily to pump water and sprayit back in the tank. Of course the tank should be vented with anoutlet protected by an insect screen.



Normally, all plumbing fixtures are fed from onecommon circuit; however this does not need to be so ifflexibility is required in order to optimize the use ofwater resources. Normally, all water that is used fordomestic applications should be of potable qualitybecause such water comes in contact with our skin andwe may even ingest some un-voluntarily when under ashower for example.

Studies in several countries have shown that water used inWC and laundry machines do not need to be of potablequality with no effect on human health. This is so becauseto a certain extent, water used in laundry machines do notcome in contact with our skin and this is more so withwater for WC flushing.

Consequently, using separate plumbing circuits allowsfeeding laundry machines and WC or at least WC withlower quality water, (Table 9).

Four plumbing configurations are proposed, these offerthe maximum flexibility in rainwater use depending onuser requirements, site conditions, plumbing designand other related factors.

PLUMBING CIRCUITCONFIGURATION

11

DEDICATED PLUMBINGNETWORKS FOR WC ANDLAUNDRY ALLOW BETTEROPTIMIZATION IN THEUSE OF WATERRESOURCES FROM ARAINWATERHARVESTINGPERSPECTIVE


35

• USECAT1 is not considered becauseit applies only to potable water forcooking and drinking thus it has aseparate plumbing network in allcases.

• PLUMBING 2C could be adoptedalso in case grey water is to be usedfor domestic purposes.

• The differentiation betweenPLUMBING 2C1 and 2C2 isnecessary to indicate whether WCare fed with USECAT3 or USECAT4water.

IMPORTANT• USECAT4 must be entered if

irrigation network is underground;in this case the RWHCAT isirrelevant.

NOTES

USECAT option

USECAT2

USECAT3

USECAT4

Remarks

All fixtures are fed from the same plumbing network, it doesnot make sense to have two plumbing circuits if one type ofwater quality is used for all fixtures.

PLUMBING2CL is the preferred option, it allows the supply ofWC and laundry with lower grade but most suitable water. Itallows maximum use of rainwater for lower quality water.PLUMBING 2C1 is the second best choice, it allows lesserflexibility in water use management but still allowsconsiderable savings in water.PLUMBING 2L is the least recommended because only limitedquantities of lower quality rainwater could be used, but still itis a viable alternative.

PLUMBING 2C2 is compulsory if USECAT4 water is to be usedfor domestic purposes.

Table 9. Plumbing Network Configurations With Respect To USECAT Options

PLUMBING1: facility has one plumbing circuit that feedsall plumbing fixtures (Lavatories, bidet,shower, WC, laundry machine, kitchen sink,dishwasher, housekeeping hose bibs)

PLUMBING2CL: facility has two plumbing circuits; onefeeds lavatories, bidet, shower, kitchensink, dishwasher, housekeeping hose bibsand the other feeds the WC and laundrymachine.

PLUMBING2C: facility has two plumbing circuits onefeeds lavatories, bidet, shower, laundrymachine, kitchen sink, dishwasher,housekeeping hose bibs and the otherfeeds the WC.

PLUMBING2L: facility has two plumbing circuits onefeeds lavatories, bidet, shower, WC,kitchen sink, dishwasher, housekeepinghose bibs and the other feeds the laundrymachine.

PLUMBING

PLUMBING option

PLUMBING1

PLUMBING2CL(best)

PLUMBING2C1(good)

PLUMBING2L(acceptable)

PLUMBING2C2


RAINWATERHARVESTINGDESIGN GUIDE

III 1INTRODUCTION

2APPLICABLE CODES, STANDARDS ANDGUIDELINES

3ADDITIONAL CONSIDERATIONS

4DESIGN AND INSTALLATION GUIDELINES

4.1 Catchment Surface4.1.a Catchment Surface Area4.1.b Catchment Surface Materials

4.2 Drains, Gutters, Leaders andDownspouts

4.2.a Sizing Drains, Gutters, Leaders &Downspouts

4.2.b Drains, Gutters, Leaders &Downspouts Materials

4.3 First Flush Tank4.3.a First Flush Tank Sizing4.3.b First Flush Tank Material

4.4 Storage Tanks 4.4.a Sizing Storage tanks4.4.b Storage Tank Material

4.5 Water Treatment4.5.a Water Treatment Equipment Sizing 4.5.b Water Treatment Equipment

Materials

4.6 Pumps 4.6.a Pump Sizing4.6.b Pump Material

5MAINTENANCE


37

This design guide deals only with rainwater harvestingsystems applicable to domestic use, external housekeepingand landscaping requirements whether for residences,schools, hospitals, governmental institutions or any otherfacility where such uses are found.

Furthermore, the guide is intended for a large spectrum of people,from those technically minded who need additional informationon the subject to those lay people that require a document thatpresents a step by step procedure how to devise, size, price andimplement a rainwater harvesting system.

This section gives detailed procedures and calculationsmethods for the different steps towards implementing aRWHS while supporting data is found in the annexes.

It is worthwhile noting here that rainwater harvesting systemsare available in many configurations therefore it is notpractical for this guideline to cover all of these if thedocument is to be kept at a manageable size. Many factorsinfluence component selection when designing or selectingthe right rainwater system for a specific end use application.Available catchment areas, water conveyance, buildingarchitectural and structural features, aesthetics, buriedutilities, soil types, slopes, site drainage, existing plumbing,electricity, routing of overflows, local regulations andneighbors are some of the many items that deserve attentionwhen considering the implementation of RWH systems.

This guideline will give the necessary information to tackleeffectively any configuration that is contemplated for aspecific project.

INTRODUCTION1

THIS SECTION GIVESDETAILED PROCEDURESAND CALCULATIONSMETHODS FOR THEDIFFERENT STEPSTOWARDSIMPLEMENTING ARWHS WHILESUPPORTING DATA ISFOUND IN THEANNEXES.


Local regulations related to rainwater harvesting systems are verysparse and deal with generalities, the only text relevant to consult isthe potable water standard found in Annex C.

- Building law 646 dated 11/12/2004 (ref:15)- Building law implementation decree 15873 (ref:16)- Environment protection law 444 dated 29/7/2002 (ref:17) - Potable water standard, decree 1039 dated 2/8/1999 (ref:18), (Annex C)

The following international codes and standards are of relevance forthose who may be interested to consult them;

- International plumbing code 2006 (ref:8)- NSF Protocol P151, Health Effects from Rainwater CatchmentSystems Components (ref:23)


APPLICABLE CODES,STANDARDS AND GUIDELINES

2

These guidelines apply to buildings at the concept stage as well asfor existing buildings. However the latter category may narrow theoptions offered in this document because the building structurealready exists as well as the plumbing works. However, if thebuilding is to be refurbished, then the guidelines could be used tomaximum advantage.

Practically, this document contains all the information required to sizea rainwater system without the need to have recourse to any othersource or document unless the user embarks in very complex systemsor wishes to consult other publications on this subject with the aim toexpand their knowledge in this field.

ADDITIONAL CONSIDERATIONS3


39

This section addresses the sizing of thedifferent components of the rainwatersystem, the selection of materials as wellas installation tips. Reference will bemade to annexes that contain thenecessary data and information toproperly perform the calculations forsystem sizing.

As previously indicated, a rainwaterharvesting system consists of thefollowing basic building blocks; acatchment surface, a conveying networkand a storage component. These will bediscussed first before tackling the twocomponents that relate to improving thequality of the harvested rainwaternamely the first flush tank and watertreatment.

4.1 Catchment Surface

A main component of rainwaterharvesting is the collection of rainwaterfrom a catchment surface. Thecatchment surface could be a buildingroof, balconies, terraces, a fully closed topparking lot pergola or even a driveway.Water quality from different roofcatchment surfaces is a function of thetype of catchment surface, roof material,climatic conditions, and the surroundingenvironment. These factors will betackled as we proceed below, howeverfirst let us find out how to compute thecatchment area.

DESIGN AND INSTALLATIONGUIDELINES

4

4.1.a Catchment surface area

The example of an individual building will be considered,however the methodology explained could be used for any typeof building or catchment surface.

The house in (fig.11) is a typical construction with a gabled roof(sloped roof) with :length A = 18.5 m and width B = 23 m which represent thebuilding footprint on the ground.

When dealing with sloped roofs, one should assume that thegables do not exist thus the building footprint dimensions arewhat matters.

Hence for this particular construction the effective catchmentarea;

Area (m²) = Length (m) X Width (m) = 23 x 18.5 = 425 m²

Fig. 11 Typical cube configuration (House 1)

NOTEFor all practicalpurposes do notworry about decimals, alwaysround to thelower number.

GabledRoof


40

Let us consider a slightly more elaborate example, an L shapedhalf gabled roof building as shown in (fig.12). Again even witha flat topped gable the golden rule still applies

Based on the above the footprint of the building in (fig.12) is;

Building Footprint Area = Effective Catchment Area =A x F + D x C = A x B + D x E

This formula was arrived at by dividing the L shaped buildinginto two parts, the long and short branches of the L shape. Thiscould be computed in two different ways depending on ourchoice of the long and short-branches.

Assuming A = 20 m, B= 26 m, C = 40 m, D = 16 m, E = 20 m,F = 10 m

Catchment area = 20*10 + 16*40 = 20*26 + 16*20 = 840 m²


Fig. 12 Typical L shape Configuration (House 2)

Regardless of the pitch, the shape, or thecomplexity of any roof surface, it is theoverall footprint of the building thatdetermines the effective catchmentarea.

GOLDEN RULE

Fig. 13 Typical House 1 Virtual RWH Roof Reservoir

Fig. 14 Typical House 2 Virtual RWH Roof Reservoir

Half GabledRoof

Now that the catchment areas are knownfor both buildings, it will be simple tocompute the potential rainwater that couldbe harvested over one rainy season.Remember from Chapter1 that rainfall wasexpressed in mm height. Thus for examplein Bhamdoun the average yearly rainfall isaround 1300mm or 1.3meters (See annexA for precipitations corresponding to yourlocation, if your exact location is not shownlook for the nearest location available anduse its precipitation data).

Imagine now that we remove the gablesof houses 1 and 2 and put instead an openair reservoir, the water collected from therain will reach a level of 1.3meters for oneaverage rainy season (assuming of courseno evaporation). What is then the volumeof water that could be collected?


41

However in practice and as seen in the previous section, thewater is not collected directly by roof reservoirs, the run-offflows on the catchment area, it is then collected by the guttersor drains then routed to storage reservoirs at lower level. Thisprocess implies water losses due to the following;

• Nearly 50% of rainwater events in Lebanon yield lessthan 5 mm of water, in such cases, not much waterreaches the storage reservoir because of evaporation onthe roof, absorption by the roof material, leakage lossesor loss in the first flush tank.

• In case of heavy rainfall, rain drops will cause splashingthus unavoidable losses.

• Also wind gusts may result in water carry over thusincreasing the losses.

•Gutters, drain pipes and water storage reservoirs may be leaky.

• Clogged drainage pipes, drains, gutters and downspoutsmay cause overflows, thus loss of collectable water.

Based on the above, it is recommended to apply the de-ratingfactors as shown in Table 10.

THEORETICALLY, FOREVERY SQUARE METEROF ROOF CATCHMENTAREA, 1 LITER OF RAINFALLCAN BE CAPTURED PERMILLIMETER OFRAINFALL.

Volume (m³) = Area (m²) x Height (m)

Based on the above formula the potentialwater that could be collected is:

For house 1 volume of harvested(collected) rainwater = 425 x 1.3 = 552 m³ For house 2 volume of harvested(collected) rainwater = 840 x 1.3 = 1092 m³

Type of roof

Gabled catchment surfaces with concrete finish, terra cotta or glazed tiles.

Flat catchment areas with concrete finish, corrugated plastic sheet, tiled finishor water proofing membrane finish.

Flat roof with gravel layer finish

De-rating factor

0.75

0.75

0.7

Estimates * : Based on several efficiency factors. - DIN 1989-1: 2001-10.Rainwater Harvesting systems-Part 1 :Planning, Installation, Operation and maintenance. 2002 “Fachvereinigung Betriebs-und Regenwassermutzung e.v.fbr.Darmstadt”

- Watershed Management Group, 2006, Calculating Runoff for Water Harvesting.

Table 10. De-Rating Factor For RWH Catchment Surfaces

Source: Author estimates *


42

Thus the effective rainwater harvestedfor both examples are respectively:

Volume of effective harvested rainwaterfor House 1 = 425 x 1.3 x 0.75 = 414 m³ Volume of effective harvested rainwaterfor House 2 = 840 x 1.3 x 0.75 = 819 m³

A de-rating factor of 0.75 was usedbecause both houses have gabled roofswith terra-cota tile finish.

4.1.b Catchment Surface Materials

The designer of a RWHS has no control overthe rainwater quality falling from the skybut he/she can influence the amount ofcontaminants transferred from the roofingmaterials to the flowing water once it runsoff the catchment surface. The selection ofroofing material is a design choice and canhave a significant effect on the quality ofharvested rainwater especially in whatrelates to toxicity. Chemical reactions oncatchment surfaces are often rapid becauseof the acidity of rainfall and sometimesbecause of the relatively high temperatureson many rooftops especially when it rainsafter a sunny interlude. These reactionsmake the choice of roofing material animportant consideration in designing arainwater harvesting system, particularly forpotable uses.

There are four types of materials thatshould not be used for catchmentsurfaces used to convey rainwaterdestined for potable use namely;asbestos, copper, lead and zinc. For otherapplications, these restrictions could berelaxed except for asbestos, thus onlyasbestos is not recommended in all cases.


• Roof materials should be preferably of smooth finishto facilitate surface flow and avoid microbial nesting.

• Pitched catchment surfaces are preferred to flatsurfaces for RWH because of higher run off velocitythus providing better surface wash.

• Provide a slope of 1% for flat catchment surfacestowards drains to ensure good run off and avoid watersettling, which is a source of pollution.

• Roofs with lead components (for example, flashing orsolder), copper, zinc or asbestos should not be used inany application with a potential for human ingestion(i.e. drinking water, pool filling, vegetable gardens).

• Green roofs are not suitable for rainwater harvesting.

• Do not mix whenever possible rainwater of differentqualities in a common storage tank.

HINTS TO CONSIDER


43

4.2 Drains, Gutters, Leaders andDownspouts

Drains and Gutters collect the flow ofrainwater from catchment surfaces to berouted by Leaders and Downspouts to thestorage reservoir. It is now high time toclarify what the four terms (Drains, Gutters,Leaders and Downspouts) are about.

Drains collect run off water, they are usedmainly for flat surfaces like a flat roof, aterrace or a driveway. Drains could have flatstrainers (fig.15), domed strainers (fig.16)or tower strainers (fig.17).

A strainer is the slotted surface wherewater enters the drain, it is slotted toprevent relatively big objects to enter thedrain and clog it. Flat strainer drains areused for locations where there is littlepossibility to have debris of relatively largesize that could block the drain strainer.

Thus flat drains are used usually indoors and also on balconies andterraces which sometimes may be the source of great annoyancedue to flooding if the strainer is clogged by leaves.Domed strainers are used on roofs and other surfaces wherethere is high probability of encountering leaves, papers andother large objects that may obstruct the drain inlet. Towerdrains are used mainly for tiled roofs where water could bedrained from the surface as well as below the tiles.

Drains are connected to leaders or pipes that convey the waterto the storage tank. Thus to the term Drain, we associate theterm Leader to mean the drainage pipe.

Gutters are more commonly associated with gabled roofs, they aremore adapted than Drains to carry out this function. While Drains arepoint collection devices Gutters are linear, they run along theperimeter of the surface to be drained at its lowest level (fig.18).Gutters usually have half circular, square or trapezoidal shapes.Downspouts are connected to gutters to conduct the water to thestorage tank (fig.18).Gutters do not usually have strainers; they are open channelsthat could collect all sorts of debris that may clog the entranceto the Downspout. Fig. 15 Floor Drain

Fig. 16 Dome Type Roof Drain

Fig. 17 Tower Type Roof Drain

Fig. 18 Typical Gutter & Downspout Configuration for a Gabled Roof

Flat strainer ontop of extension

Downspoutentrance couldbe easilyclogged bydebris

Slot strainer atbottom ofextension

Gutter

Downspout

Leader

Flat strainer

Domed strainer


44

(Table 11) returns the size of horizontalleaders for a given slope and catchmentarea based on a maximum rainfall rate of50 mm/hour. The slope is the amount ofinclination of a horizontally running pipeexpressed as vertical drop per meter ofhorizontal run, thus 1% slope is a drop of1 cm per 100 cm of pipe run.

In the case of house 1, if the 110 mmvertical leader is to be routed horizontally,it is necessary to have a slope of 2% if ithas to serve the area of 425 m². In(Table 11) the maximum catchmentsurface area served by a 110 mmhorizontal leader with 2% slope is 492 m².If it is impossible to run a 2% slopebecause of obstructions and only a 1%slope is possible then the leader sizeshould be increased to 125 mm.

4.2.a Sizing Drains, Gutters, Leaders and Downspouts

Sizing of Drains, Gutters, Leaders and Downspouts is fairly easybut should be properly done to maximize the quantity ofharvested rainwater and avoid spill overs, overflows and othermalfunctioning. Let us consider the two houses of the previoussection. Suppose the houses have flat roofs, therefore makingdrains a more suitable proposition.

Drains are specified by their connection size, hence a 4 inch(110mm) drain connects to a 4 inch pipe or Leader. As a rule ofthumb, every 200m² of projected roof area requires a 110mmdrain. Actually the present guidelines do not recommend roofdrains of smaller size even for roof areas less than 200m². Thusif a roof has a projected area of 300 m² then allocate one110 mm drain for each 150 m². The roof slopes should beworked out accordingly.

Thus for house 1 based on an area of 425m², 2x110mm drainswill be most appropriate. House 2 has a catchment area of 819m², thus 4x110mm drainsshould be provided.

We have now the size of the drains and vertical leaders. Whatabout if the Leaders should run horizontally to reach therainwater harvesting storage tank?


DIAMETER OF HORIZONTALPIPING (inches)/mm

HORIZONTALLY PROJECTED ROOF AREA (m²)FOR A RAINFALL RATE OF 50 mm/hour

(4)/110

(5)/125

(6)/150

(8)/200

4 % SLOPE

699

1,241

1,988

4,273

Table 11. Sizing Of Horizontal Leaders - (Ref:8)

Source: IPC 2006

3 % SLOPE

595

1,059

1,695

3,651

2 % SLOPE

492

877

1,403

3,028

1 % SLOPE

349

621

994

2,137


45

Sizing Gutters follows the samemethodology but involves additionalconsiderations. (Table 12) is used to sizesemi- circular gutters but any guttershape could be accommodated by usingthe equivalent circular size which is thecircle that could fit inside thecontemplated shape.

Thus if a rectangular gutter can accommodate a 110mm circle,then it has a 110 mm equivalent circular size. In other words itis equivalent to a 110 mm semi-circular gutter.

Gutters are sized by sections because each section serves onegable. It is not recommended to have flow direction change ina gutter. Thus if Gutters drain the gabled roof of house 1, onestraight run will drain each side of the gable, however thedownspouts at the extremities of two adjacent gutters could bejoined into one downspout (fig.20).

Moreover even though there may be fourgables, but in no case should theallocated catchment area for any onesection of gutter serving one gable beless than half the projected area of theroof.

As a practical example, consider againhouse 1, each gable face will be drained byone gutter, the two adjacent gutters of faces1 and 2 will be sloped towards each otherand their downspouts will be connected.The same happens for faces 3 and 4.

DIAMETER OF GUTTERS (inches)/mm

HORIZONTALLY PROJECTED ROOF AREA (m²)FOR A RAINFALL RATE OF 50 mm/hour

(3)/90

(4)/110

(5)/125

(6)/150

(7)/180

(8)/200

(10)/250

0.50% SLOPE

32

67

116

178

256

370

669

1% SLOPE

45

95

163

253

362

520

948

2% SLOPE

63

134

232

357

513

739

1338

3% SLOPE

76

162

281

436

619

890

1598

4% SLOPE

89

190

329

515

725

1040

1858

Table 12. Sizing Of Gutters - (Ref:8)

Source: IPC 2006

The de-rating factor used to compute the potentialrainwater quantity that could be harvested does not applywhen sizing drains, leaders, gutters and downspouts forrainwater harvesting.

IMPORTANT TO REMEMBER


46

It is important to note that downspoutscannot serve more than 20 meters ofgutters length, this is so because of flowconditions and the probability of clogginga downspout because of debris.

Going back to the example of house 1,one side of the building has a lengthhigher than 20 meters, thus it isimportant to have two downspouts persection of gutter serving that side.

Each downspout is sized based on thearea served by the gutter, thus for the firstsection serving an area of 215 m², it willhave two downspouts of 110 mm each.If a rectangular downspout is to be used,then its smaller side should be no lessthan 110 mm.

Moreover, It is possible to join twostretches of gutters into a singledownspout as long as the gutters havetheir individual downspouts outlets(Fig.20) and the downspout is sizedaccordingly taking into consideration thetotal area of gables being drained.


Fig. 19 View of a Rectangular Downspout

Rectangulardownspout

Circular gutterdraining intotherectangulargutter below

Rectangulargutter

Fig. 20 Detail of a common Downspout

Gutter and downspout made ofPVC, this type of material is notrecommended for locations withhigh solar exposure

• Straight sections of gutters served by two downspouts should haveopposite slopes starting at their middle.

• The outside face of the gutter should be lower than the inside faceto encourage water flow away from the building wall.

• Half-round or trapezoidal gutters are preferred for rainwaterharvesting because of more efficient drainage. Square orrectangular sections should be avoided; they are more difficult toclean.

• It is preferable to increase the slope of the gutter by 0.5% on the last1/3 length of the gutter before the downspout.

• Downspouts shall serve no more than 20 mof gutter length.

HINTS TO CONSIDER

Any gutter of house 1 will be sized to drain a catchment area425/2 m² or 212 m². Assuming a 1% slope is selected,(Table 12) gives a diameter of 150 mm.

Downspouts sizing is rather straightforward, these should havethe same circular size as the gutters they drain. It is importantto note that downspouts may have rectangular shapes (Fig.19).In such cases the rectangular downspout will be consideredequivalent to a circular pipe having a diameter equal to thesmallest side of the rectangular downspout. For the rectangulardownspout shown in the below photo it is 110 mm, thus thedownspout was considered equivalent to a 4 inch pipe.


47

oxidize thus it should be ruled out if the intent is to use rainwaterfor domestic purposes. The choice in order of decreasingpreference is stainless steel, aluminum, epoxy coated sheetmetal and last galvanized sheet.

Gutters with built in wire mesh as cover is an excellent idea asit will greatly reduce the probability of leaves and other solidobjects entering the waterways thus clogging the gutter.

Regardless of material, other necessary components inaddition to the horizontal gutters are the drop outlet, whichroutes water from the gutters downward through thedownspout pipe. Additional components include supportbrackets and straps which could be of similar material as forgutters and downspouts. Use fasteners that do not rust toavoid rust smearing on the fascia and walls.

4.3 First Flush Tank

This device shown in figures 22-23 below serves to divert towaste the first rains of each rainfall event which are usuallyladen with contaminants carried over from the catchment arealike dropping, dust, leaves, blooms, twigs, insect bodies,pesticides and other airborne residues.

The tank is sized to flush the equivalent of around 1.5 mmheight of rainfall. It will then automatically rout the relativelyclean rainwater to the storage tank. This device has two mainadvantages;

• It saves the trouble of having to divert the first rainsmanually, a practice that wastes rainwater. This isespecially so because rainfall events in Lebanon aresometimes separated by a relatively lengthy dry period thatmay extend for weeks, the catchment surface flushingneeds to be performed at the onset of nearly eachimportant rainfall event.

• It improves rainwater quality that enters the storage tank,thus enabling a greater flexibility in its use while saving onwater treatment.

4.2.b Drains, Gutters, Leaders andDownspouts materials

Drains for external surfaces comemostly in three constructions for thebody and the strainer, namely PVC, PEor cast Iron. It is recommended to usecast iron drains with cast iron strainersfor exposed surfaces to the sun.

Gutters, Leaders and downspouts couldbe PVC, galvanized sheet metal, epoxycoated sheet metal, anodized sheetmetal, copper, seamless aluminum oreven stainless steel. It is recommendednot to use PVC for exposed componentsas it structurally weakens if continuouslyexposed to the sun’s rays. Copper may

• For domestic rainwater useincluding potable waterapplications (USECAT1 & 2), leadcannot be used as gutter solder.Rainwater acidity could dissolvelead and thus induce leadcontamination. Certified soldermaterial should be selected.

• Where possible, locate the Leaderor downspout near the location ofthe rainwater storage tank.

HINTS TOCONSIDER


48

It is recommended not to exceed acatchment area of 200m² per tank. Thusfor a catchment area of 350 m² of sameRHWCAT, it is recommended to have twotanks operating in parallel. each sized forhalf the projected area.

4.3.b First flush tank material

For underground installations, a masonryor reinforced concrete body isrecommended while the trim (Tankcover, strainer, run off plate, ball holdingplate, threaded rods) should bepreferably galvanized steel or epoxycoated steel. The ball should be of goodquality plastic or alternatively brass.

For aboveground installations the bodymay also be made of galvanized steelespecially if the first flush tank is installednear ceiling level in mechanical room.


The method of operation of the first flush tank is extremelysimple and practically trouble free if the tank is cleaned at theend of the rainy season. The inlet water is intercepted by astrainer that retains all objects bigger than 2 mm. The waterthen runs off the sloped plate below the strainer and into thewaste chamber through the 90 mm center hole.

The water exits the bottom of the tank at a very low flow rate(thru the Ø32 mm drain pipe or by percolation) thus resultingin an increase in water level which raises the 100 mm plasticball till it closes completely the center hole thus diverting thewater to the tank outlet and into the storage tank (fig.21).

The first flush tank could be installed below ground or aboveground depending on the system configuration. (fig.22A/22B)

For optimum water use, the waste water from the first flush tankcould be stored in a separate tank that could be used forirrigation purposes. This tank needs to be cleaned yearly ofdeposits.

For Construction details see Annex F.

4.3.a First flush tank sizing

The sizing is fairly straight-forward, the only dimension requiredis X which is for one side because the tank has a squareconfiguration. X is given as a function of catchment area asfollows;

X = 0.005*S where S is the projected surface of the catchmentarea. Thus for a 200 m² catchment area, (S=200), X = 0.005*200 = 1 m

Fig. 21 Detail of First Flush Tank Operation

FOR OPTIMUMWATER USE, THEWASTE WATERFROM THE FIRSTFLUSH TANK COULDBE STORED IN ASEPARATE TANKTHAT COULD BEUSED FORIRRIGATIONPURPOSES.


2mm Checkered Plate GalvanizedSteel Cover

X

Removable 1.5mm Galvanized Steel plate to give 5% slope towards center supported by galvanized steel angle strip bars on 4 sides

Inlet Pipe Ø110mmfrom Catchment Area

Internal square Tank measurement

PVC Pipe

RemovablePlastic Mesh screen (2x2mm) with Aluminum frame 40x10mm.Supported by 20x20 galvanized steelangles on 4 edges

Ø32mm Drain lineat corner 150 mm from walls

2x Outlet Pipes Ø110mm eachShort radius elbow

To RWH Tank

FF Tank 100mm Reinforced Concrete casing for underground installation

Ø8mm Galvanizedsteel threaded rods

Ø100mm Plastic Ball

150mm

400mm

150mm

50mm

30mm

50mm110mm

150mm

150mm100mm

90mm

200mm

49

Fig. 22 A Detail of Underground First Flush Tank

X

Removable 1.5mm Galvanized Steel plate to give 5% slope towards center supported by galvanized steel angle strip bars on 4 sides

2mm Checkered Plate GalvanizedSteel Cover

2x Outlet Pipes Ø110mm eachShort radius elbow

To RWH Tank

150mm

400mm

150mm

50mm

30mm

Ø32mm Drain lineat corner 150 mm from side

FF Tank 1.5mm Galvanized Steel plate for above ground installation

Ø100mm Plastic Ball

Ø8mm Galvanizedsteel threaded rods

RemovablePlastic Mesh screen (2x2mm) with Aluminum frame 40x10mm.Supported by 20x20 galvanized steelangles on 4 edges

Galvanized sleeve

Inlet Pipe Ø110mmfrom Catchment Area

Internal square Tank measurement

150mm100mm

90mm

200mm

50mm110mm

Fig. 22B Detail of Above Ground First Flush Tank


50

4.4.a Sizing storage tanks

While rainwater harvesting has a numberof environmental benefits, it must also beeconomically viable to enter themainstream of building practices. Becausethe tank is often the most expensivecomponent of a rainwater harvestingsystem, decision-making on tank size canhave a strong impact on the economicfeasibility of rainwater harvesting.

The size of storage tanks is dictated byseveral variables including:

• Rainfall in the area considered • Projected daily water demand • Length of dry season • Catchment surface area • Aesthetics, personal preference • Budget.

No doubt the Length of the dry period isone of the most important governingfactors in the design of a RWHS inLebanon which experiences a dry seasonthat extends over some 7 – 8month. Thisis not the case for countries further westlike Europe where rain hardly stopsaround the year. Consequently, rainwaterharvesting tanks in Lebanon should be ofrelatively large size if one plans to userainwater as a source of water supply.

The sizing process starts by determiningwhat use will be made of the rainwaterand the quantity required. This guidelineproposes four use categories defined inChapter 2. The decision on the usecategory should be made based on theavailability of corresponding catchmentareas. For example it does not make

4.4 Storage Tanks

The storage tank or cistern generally is the most critical designcomponent of a rainwater harvesting system. In most cases itis permanent and its placement should be carefully thought out.

Tanks can be placed either above or below ground. For bothoptions, water should be able to gravity feed to the tank.Locating the tank near the building and the water use reducesthe amount of pipe and site work necessary as well aspumping demands. Though no hard and fast rules govern thedecision of aboveground or belowground tanks, in general,once the storage volume exceeds 10 m³ belowgroundstorage is often the most viable option. Beyond this, tanklocation is dependent on aesthetics, climate and soilconditions. However, placing tanks underground ads to theinstallation costs and may be limited in areas where soil isespecially rocky or areas with a high water table. When tanksare installed below ground, water is maintained at a cooltemperature and light is blocked, which reduces the chancesof bacterial growth.

Existing structures should be considered when installing aRWH system. Water is normally conveyed from thecatchment area to storage tanks by gravity. Think carefullyabout the location of drains, gutters and downspouts tomaximize the use of existing installations and to collect waterfrom a roof area that will support water demand. For aboveground installations, the tank foundation must be flat, andcapable of supporting the weight of maximum storage.Locate tanks in areas that are not subject to erosion, floodingor other factors that might undermine the integrity of thefoundation. Consider how electricity can be delivered to thepump of the RWH system, and how rainwater supply lines canbe safely added to existing plumbing.

More than one storage tank may be considered if catchmentareas and site conditions dictate that decision or ifsegregation of collected rainwater by quality is planned. It isa waste to mix a RWHCAT1 source with a RWHCAT3. Forexample the tank could have different compartments toaccommodate each rainwater category.



51

As an example, consider that house 1 isoccupied by a family of 6 persons and hasa garden having 25 m² of green lawn(gazon) as well as 250 m² planted with60 shrubbery and Trees. The ownerdecides to have USECAT1 and USECAT2for domestic purposes (including carwash, external surface cleaning) and forthe lawn (sprinklers) and USECAT3 fortrees and shrubbery (drip). The rainwatersupply should be enough to cover5month of consumption (Tc = 5month)which is the period when municipalwater supply is somewhat reduced andowners do not want to take the risk of

relying on private tankers. The owners did not install aswimming pool, not because they lack the means but becausethey believe it is a luxury the water supply condition of thecountry cannot afford. The owner is very conscious about watersaving, therefore all plumbing fixtures are water saving type aswell as the dishwasher and laundry machine.

RWHCAT1 catchment surface will be used to supply USECAT1,USECAT2 and USECAT3 because the roof of the house complieswith all requirements for RWHCAT1. No other surface isavailable for harvesting other than the driveway and owner doesnot wish to use it as catchment area.

RWHCAT1 supply is calculated as per Tables 13/14/15 belowusing data from Annex D.

economic sense to decide on a USECAT1or even USECATE2 if only a RWHCAT3 orRWHCAT4 area is available.

Once this decision is made, the requiredquantity of water could be determinedusing the demand table in AnnexD and thetime coverage. The table gives water

demand data based on demand type detailed down to the type offixture used, use category, use type (Domestic, irrigation, car wash),types of plants for irrigation, irigation type (sprinkler, drip, hose,underground), use mode (water saving or normal) and application(residential, school, hospital, etc.), based on these choices one canread the required water demand. Column 8 (plumbing) is notrequired for determining water demand but rather it shows thetype of plumbing installation necessary for certain applications.

Fig. 23 Storage Tanks

RWHCAT1 supply

USECAT1 (Drinking, Cooking)

USECAT2 (Domestic saving mode)

Total m³

2.7

76

Table 13. House 1 Domestic Water Consumption

Period (days)

150

150

Persons

6

6

Demand (l/p/d)

3

85


52

In all cases, the tank should overflow atleast once a year so that floating debrisare drained away from the watersurface.

There is a point of diminishing returnsbeyond which increasing the tank sizeprovides only a marginal benefit, in thecase of House 1, the optimum size isactually 200 m³.

Use of blending with municipality water

If blending is contemplated thusextending the period of use of soft waterin case rainwater is in limited supply orthe RWH tank needs to be downsized,municipality water is equally blendedwith rainwater thus cutting by half theRWH tank capacity. Sizing of themunicipality water storage tank will bedone as follows.

Check the Municipality Water Availability(MWA) in your area according to theclassification shown in Table 16 below;

The total water demand of the house is 116 m³ which is therainwater storage quantity required assuming municipalitywater is not used during the coverage period. The rainwaterquantity required is well within the potential 414m³ that couldbe collected on an average rainy year. Actually rainwater couldcover house 1 needs even in the dry years when rainfall couldreach 40% of the yearly average.

It is worthwhile noting that the 25 m² of green lawn consumetwice as much as the 250m² of shrubbery and 1/3 of the overalldomestic consumption. Green lawns could be a nice thing butthey are practically an environmental disaster from a waterconsumption viewpoint in the Lebanese context.

Thus for house 1 a 150m³ nominal volume underground RWHstorage tank is required, nominal volume being the physicalvolume of the tank and not the effective water holding capacity.As a rule of thumb physical volume should be 20% larger thaneffective holding capacity, mainly to allow for the sedimentationzone at the bottom (approximately 10% of tank volume) andthe overflow clearance at the top section of the tank.

Because the roof catchment capacity is larger than reservoircapacity, the reservoir will overflow once filled up and thesurplus water will be directed to the storm drainage network.Or alternatively, the owner could decide to extend the period ofuse to seven month and build a 200 m³ storage tank.


RWHCAT1 supply

USECAT2 (Sprinkler for green lawn)

Total m³

26

Table 14. House 1 Irrigation Water Consumption Sprinklers

Period (days)

150

Area m²

25

Demand (l/m²/d)

7

RWHCAT1 supply

USECAT3 (Shrubbery and trees)

Total m³

13.5

Table 15. House 1 Irrigation Water Consumption Shrubberies/Trees

Period (days)

150

Shrubs pcs

60

Demand (l/shr/d)

1.5


53

Based on the MWA classificationobtained from Table 16 above, on theoverall daily water demand of thefacility (Dw) and on the coverageperiod required (Tc), the municipalitywater storage tank effective volume(Vm) could be computed according tobelow;

1. Case 1: If MWA = High, Vm= 20 m³ if the facility water demand for 20 days is less than 20 m³, Otherwise,Vm = 20*Dw

2. Case 2: If MWA = Medium Vm = 30*Dw if Tc > 4 month,Otherwise,Vm = 20*Dw

3. Case 3: If MWA = LowVm = 50*Dw if Tc > 6 month,Otherwise,Vm = 30*Dw

4. Case 4: If MWA = Very LowVm = 70*Dw if Tc > 6 month,Otherwise,Vm = 50*Dw

Table 16. Classification Of Municipality Water Availability

DESCRIPTION

Municipality water is available: • All year round at least once every two days for at least 5 hours

Municipality water is available: • November – May: at least once every three days for at least 5 hours• June – October: at least once every four days for at least 5 hours

Municipality water is available:• November – May: at least once every three days for at least 5 hours• June – August: at least once every four days for at least 5 hours• September – October: once every week for at least 5 hours

Municipality water is available: • November – May: at least once every three days for at least 5 hours• June – August: at least once every four days for at least 5 hours• September – October: Municipality water is Ooccasional or completely cut off

Facility is not connected to the municipality network or municipality water is occasional

MWA

HIGH

MEDIUM

LOW

VERY LOW

NONE


54

of USECAT4 demand which couldconsist only of irrigation water or waterfor WCs or alternatively a combinationof irrigation water and water for WCs.

The Table in Annex D can be used todetermine USECAT4 demand of thefacility based on the choices made bythe occupants.

The Effluent grey water and rainwaterquantity required for blending should becomputed based on an equalpercentage blending.

Back to house 1, suppose the occupantswould like to use the grey water forirrigation and WC. Typically, grey waterfrom lavatories and showers amountbetween 35% to 40% of domestic waterconsumption, while WC consumption isequivalent to some 30% of domesticwater consumption. From Tables 13, 14and 15 above, irrigation amounts to 52%or domestic water consumption,consequently grey water even ifblended cannot meet the irrigation andWC consumption requirements.

Consequently, blending should be donewith a higher rainwater contribution.The reduction in rainwaterrequirements is around 76*0.35 = 27m³. (See table 12 above)

GWT size should not be higher than thedaily USECAT4 consumption, in our caseit should be sized as (26 + 13.5 +76*0.4)/150 ~ 0.5 m³ (as nominalvolume). Whatever inflow exceeds theholding capacity of the GWT will overflowto the sewer system of the facility.


The volume of the tank is obtained by multiplying the effectivevolume computed above by 1.2

Going back to house 1, suppose the occupants are interested inblending for cost reduction considerations given thatmunicipality water is fairly available. The occupants considerthat the MWA could be rated as low however to be on the safeside they opt for a very low MWA.

Based on a Tc = 5 month, Dw = 116/(5*30) = 0.77 m³/day This is case 4 with Tc < 6 month, accordingly Vm = 50*0.77 ~40 m³ for rounding purposes.Thus the savings in storage volume is = 1.2*(116/2 - 40) = 22 m³

Note: the factor 1.2 is used to compute actual tank volume giventhe effective water volume to be used.

Use of grey water

Suppose the occupants of a facility wish to use grey waterblending in a USECAT4 application, the purpose being toenhance the quality of the effluent grey water from the greywater treatment plant. The first step should be the evaluation

Fig. 24 Typical blending tank configuration

Blending tank

Feed line fromMunicipalityWater tank

Feed line fromRWH tank

Municipalitywater andrainwater tankstransfer pumpsare interlockedand are equallysized hencedeliveringequal amountsof water to theblending tank


BP

TP

From Catchment Surface *RWHCAT4

GWTFrom grey watertreatment plant

RWHT

To USECAT4 network

Overflow line to sewer

125 m³

0.6 m³

55

The transfer pump TP should be timed todeliver 15% of GWT capacity every hourbetween 8am and 10pm, hence in our caseif the pump flow is rated 1.5 m³/hr, thenpump should operate for 0.15*0.5/1.5 =0.05 hour or 3 minutes/hour. Howevertiming could be modulated according to thefacility schedule and occupancy theobjective being to approach as much aspossible the targeted blending ratiobetween the rainwater and grey water. Ofcourse the GWT should be equipped with alow level pump actuation in order to operateTP if tank is empty.

Level control in storage tanks

Storage tanks should be equipped withhigh/low level alarm float switches forpump protection and provide warning ofmalfunctions. For monitoring purposestanks should be equipped with levelindication systems consisting of a levelsensor located in the tank and a level displaydevice located in an easily accessiblelocation. The display device could have leadlights that indicate tank level status.

Fig.25 Grey water blending schematic example

• Aboveground tanks should be opaque to prevent algaegrowth, UV resistant to prevent tank failure, and pipingshould be protected against freezing.

• Belowground tanks must be appropriately load-rated forthe site (i.e. under a pedestrian area or a parking lot).

• Tanks should be installed according to manufacturers’instructions.

• Only watertight tanks designed for storage should be used

• Tank should not have been used to store any other material.

• Tank should be sized according to the planned RWHCATand the demand for corresponding USECAT.

• Tank should have an access opening minimum 450mm tofacilitate installation, inspection and maintenance ofcomponents within the tank.

• For cases where venting by means of conveyance drainagepiping and overflow drainage piping is consideredinsufficient, a vent shall be installed, with a min height of150mm above grade and no less than 75mm in sizeequipped with a gooseneck bend andinsect screen.

HINTS TO CONSIDER



HINTS TOCONSIDER• Tank should be provided with acalming inlet located at the bottom, itis used to direct the entering waterupwards to prevent disturbing thefine particulate matter on the bottomof the tank. Calming inlets alsointroduces oxygen into the bottom ofthe tank.

• Underground tanks should have asump for drainage

• Tanks should have an overflow of atleast the same diameter as the inletpipe. Overflow should be routed tothe storm network and not thesewer network. Overflow should betrapped if tank is for USECAT1 orUSECAT2 applications.

CASE 1:Rainwater is used only during the dry season (from May onward)- If facility water demand for the planned period during the dry season ishigher than the possible RWH volume, then tank effective volumeshould not exceed the corresponding effective surface catchmentcapacity for an average year.- If facility water demand for the planned period during the dry season islower than the possible RWH volume, then tank effective volume shouldbe equal to the facility water demand for the planned period.- The storage tank nominal volume should be 20% larger than theeffective rainwater volume required. Tank physical dimensions arebased on the nominal volume.- If blending with municipality water is contemplated, then RWH tankvolume could be cut by half compared to the case of no blending buton the other side a municipality water storage tank needs to be providedand sized according to the procedure shown above.- If grey water is to be used, then the RWH tank volume could be reducedby the volume of grey water used for irrigation and/or WC flushing.

CASE 2: Rainwater is used during the rainy as well as dry season (FromDecember onward) - If facility water demand for the planned period during the wet and dryseason is higher than the possible RWH volume, then tank effectivevolume should not exceed 60% of the corresponding effective surfacecatchment capacity for an average year.- If facility water demand for the planned period during the wet anddry season is lower than the possible RWH volume, then tankeffective volume should be equal to the facility water demand forthe planned period.- The storage tank nominal volume should be 20% larger than theeffective rainwater volume required. Tank physical dimensions arebased on the nominal volume. - If blending with municipality water is contemplated, then RWH tankvolume could be cut by half compared to the case of no blending buton the other side a municipality water storage tank needs to be providedand sized according to the procedure shown above.- If grey water is to be used, then the RWH tank volume could be reducedby the volume of grey water used for irrigation and/or WC flushing

RAINWATERSTORAGE TANK

SIZING PROCEDURE


57

4.4.b Storage Tank Material

Rainwater storage tanks construction couldbe of different material, such as concrete,masonry, epoxy coated steel, stainless steel,galvanized sheet metal, Polyethylene orfiberglass. The characteristics of theinstallation such as above or undergroundconfiguration, indoors or outdoors, size aswell as end use of the stored rainwater doinfluence the choice of material and typeof construction.

Concrete tanks are sturdy, provideextreme flexibility in shape, size,configuration and internal design. Theycould be either cast in situ orprefabricated for above or undergroundinstallation. Cast-in-place tanks can beintegrated into new construction undera patio or a basement, they will thusform an integral part of the buildingstructure. For existing buildings, addinga concrete tank requires the expertise ofa structural engineer to determine thesize and spacing of reinforcing steel tomatch the structural loads. Concretetanks may be prone to cracking andleaking, especially if built on weakfoundations like clay soils. One otheradvantage of concrete tanks is that theyalso neutralize the acidity of harvestedrainwater and by doing so impart adesirable taste to the water thanks to thedissolved carbonated compounds. ForUSECAT1 systems, it is essential that theinterior of the tank be finished with foodgrade plaster and paint.

Polyethylene: A wide range of selectionis available with multiple sizes. They canbe used above and below ground

according to specifications. They exist in single, double andtriple layers, with vertical and horizontal models. Fittings ontanks are easily installed. Some models are food grade approved,good for potable water storage.

Stainless Steel type 316 is an excellent choice for USECAT1applications but pricey, good for above ground applicationsespecially if indoors, however sizes above 8 m³ may beproblematic as far as construction is concerned. The grade ofthe stainless steel should be carefully selected, many tankmanufacturers in Lebanon make claims they do not meet as faras stainless steel tanks are concerned. A bad selection ofstainless steel grade or bad workmanship will result in theunpleasant surprise of a corroded tank 6 month afterinstallation.

Fig. 26 Polyethylene Tanks

Underground PE tank Triple Layer PE Tank

Underground Modular PE tank

RAINWATER STORAGETANKS CONSTRUCTIONCOULD BE OFDIFFERENT MATERIAL



if not properly constructed it will suffersevere corrosion at the seams.

Galvanized Steel is cheaper but suffers the same limitations asstainless steel as far as sizes limitations are concerned, moreover

with valves) connections are clearly seen.The pipes above the drain lines are thepump feed lines.

(Fig.27 shows 3x4 m³ 316 stainless steel tanks as well as 1x500liter potable water tank (lower rightmost) The overflow (top most pipes) and drainage (lower most pipes

Overflowpipes

Watersupply pipe

Drainagepipe

Second stagewater treatment(see section3.4.5 below)

Drainage pipes

Potable water booster system

Fig. 27 Stainless Steel Tank

Table 17. Tank Materials Evaluation

Advantages DurableLasts very long Suitable for Above or Belowground installationsNeutralizes acidic rainwaterImparts desirable water taste

Commercially availableAffordableAvailable in variety of sizesEasy to install Above or BelowgroundLittle maintenanceTriple layer, Insulated, UV resistant & food grade, no coloring inside, maintains pureness of water inside.Underground modules/ unlimited capacity.Alterable & movableCommercially availableLittle maintenanceAlterable & movable

Commercially availableAlterable & movable

Tank Material Poured in placePrefabricated

Polyethylene

Stainless Steel 316

Galvanized Steel

DisadvantagesPotential to crack or leakImmovable

UV degradable Must be painted ortinted

Expensive Size limitations

Possible corrosion andrust, that can lead toleaching of metal

Conc

rete

Met

alPlas

tic


Front ViewSide View

30 cm

Calming Inlet

Water trap

Inlet funnel

Fig. 29 Tank Overflow

Fig. 28 Calming Inlet

59

Tank should be provided with a calming inlet (fig.28) routed tothe tank bottom, it is used to direct the entering water upwardsto prevent disturbing the fine particulate matter settled at thebottom of the tank. Calming inlets also introduces oxygen intothe bottom layers of the tank.

All tanks should be provided with overflows (fig.29) connected tofacility drainage network through a water trap or a positive airbreak to avoid contamination.

It is preferable that drain inlets be funneled to ease the waterflow. Funnel diameter to be three times the overflow pipediameter.

4.5 Water Treatment

The general public is often leery aboutconsuming and utilizing rainwater forpotable and/or non-potable use, but propersystem design with strict implementationand monitoring makes harvested rainwatera safe water source. Crossing thepsychological barrier is a real challenge.

The environment, the catchment surface,the conveying network and the storage tankscan affect the quality of harvested rainwater.Unnecessary degradation of collectedrainwater can be minimized through goodhousekeeping but this is not enough ifrainwater is to be used for domesticpurposes (USECAT1/USECAT2) even ifRWHCAT1 catchment surfaces are used.

Water treatment is a complex discipline,however for the purposes of this guidelineand the applications involved we can narrowwater treatment to few basic componentsnamely straining, sedimentation, filtration,chlorine sterilization, carbon adsorptionand UV polishing. These will be discussedhere below.

Straining and sedimentation effectivelybelong to pre-treatment stages. Strainingoccurs at the first flush tank where relativelylarge size objects and bulk pollution isremoved before reaching the storage tank.

Sedimentation occurs in the storage tankwhere particles settle to the bottom due togravity, For sedimentation to be effective, thewater body should not be agitated, this is thereason why inlet calmers are devised tominimize water agitation when freshrainwater enters the tank. Several days are


60

required for suspended particles to settle down to the tankbottom. Sedimentation can remove up to 80% of the particlesentering the tank.

Consequently the storage tank should be cleaned at least once everythree years if a first flush tank is used and once every year if a flush tankis not used.

Pressure filtersThe first water treatment stage is filtration; filters could be of differenttypes, for our purpose, only media type pressure filters are usedfollowed by micro filters. Media filters are filled with sand or any othersmall grain media that retains suspended particles in the water thatdid not settle in the storage tank like pollen, coarse dust particles,human hair, etc. Media filters remove particles 5micron and larger,this is practically 95% by weight of all suspended particles and bydoing so these filters remove a lot of biological pollutants becausethese usually adhere to solid particles.

Media Pressure filters could be elongated cylinders or spherical inshape (fig.30).

Micro FiltersMicro filters or cartridge filters are installed downstream ofmedia filters, their task is to remove the fine particles down to0.5 micron size range that media filters cannot remove. Theyare made of tightly interwoven natural or synthetic threads thatstop very fine dust and other pollutants particles like insecticidedust. For the sake of comparison, the thickness of a human hairis around 100 microns.


Fig. 30 Pressure Filters Fig. 31 Micro Filters

THE STORAGE TANKSHOULD BE CLEANEDAT LEAST ONCEEVERY THREE YEARS

Micro filter woven fabriccore, it is placed inside the micro filter.

The core is replaceableonce it gets clogged withsmall particles itremoves from the water

Micro filterbody

UV sterilizer


61

Chlorine SterilizationFilters remove solid particles and in theprocess they remove somebacteriological pollution adhering tothese particles, but filters are notdesigned to remove effectivelybacteriological pollution like viruses. Thisis the job of chlorine sterilization. Usuallya solution of sodium hypochlorite isinjected in the pipe work upstream of themedia filter. For that purpose, ahypochlorite tank (Fig.32, right picture)and a dosing pump (Fig.32, left picture)are used.

The injection pump draws the solutionfrom the tank and injects it in thepipework upstream of the blending tankif one is installed. The injected chlorinewill sterilize the media filter as well as themicron filter. Chlorine should never beadded in the RWH storage tank.Keeping a 0.1 mg/l concentration ofchlorine in the system is recommendedat this stage as the water may spendfew days in the treated tank or even inthe rooftop reservoir if there is one.

The dosing pump should be interlockedwith the RWH storage tank transfer pumpas well as with the municipality tanktransfer pump if blending is carried out.

At this stage the treated water is fit fordomestic use but not for cooking ordrinking. The treatment above issatisfactory for USECAT2 if RWHCAT1 orRWHCAT2 is available. The treated watercould be stored in a treated water tankpreferably made of stainless steel or PE.The treatment discussed above is calledfirst stage treatment in this guideline.

Carbon filtersAs a polishing stage, carbon filters are installed to remove anytraces of hydrocarbon pollution like pesticides, sub- micronlevel particles as well as the remaining chlorine in the water.Carbon filters look exactly like media filters. They may or maynot be installed downstream of the first stage treatment.

If some of the product water is to be used for cooking ordrinking then a second stage treatment is required. Some ofthe water is pumped from the treated water tank into anothermicro filter (on the left of the picture (Fig.34) then passedthrough an Ultra Violet sterilizer (center of picture withbypass for maintenance purposes) then the water is stored ina potable water tank (The top of the stainless steel potablewater tank could be seen at the bottom of the picture) Theproduct water is fit for drinking or cooking purposes. It is nowUSECAT1. The carbon filter if not installed directly after thefirst stage treatment could be installed downstream of themicro filter in the second stage. The second option may allowa smaller size carbon filter.

Fig.33 below shows a general view of a first stage treatmentwith a downstream carbon filter for a RWHCAT2 catchmentarea destined for a USECAT2.Raw water from the blending tank enters the first stage watertreatment from the right of the picture.

Fig. 32 Chlorination dosing pump & Hypochlorite Tank


62

could be partly seen at the top right of thepicture. It injects chlorine upstream of themedia filter in the blending tank (notappearing in the picture).The product water is routed to thedomestic water 316 stainless steel tank.

Fig.34 shows a second stage treatment butwithout carbon polishing which wasinserted in the first stage. Water from thedomestic tank at the left of the pictureenters the micro filter then the UV sterilizerbefore entering the potable water tankwhich top is seen in the picture.

• The first and second stages of watertreatment described above form WTCAT1.

• WTCAT2 is equivalent to a first stagetreatment.

• Carbon filters may be installed after thefirst stage treatment or they may formpart of the second stage treatmentdepending on preferences. Carbonfilters are recommended only ifUSECAT1 is contemplated.

• WTCAT3 consists basically of the firstflush tank and the settling in thestorage tank. Consequently WTCAT3 iseffectively a pretreatment withoutfiltration or sterilization.

Rightmost is the media filter followed by the smaller size microfilter then the carbon filter on the left of the picture. Thehypochlorite tank is seen below the micro filter while thehypochlorite dosing pump is fixed to the wall above the mediafilter. The plastic tubing connecting the hypochlorite dosing pumpto the hypochlorite tank is the suction line, while the injection line


Fig. 33 1st Stage Water Treatment Configuration with Down Stream Carbon Filter

Hypochloritedosing pump

Pressure filterautomaticbackwash valve

Media pressurefilter

Micro filter

Carbon filterautomaticbackwash valve

Carbon filter

This filter couldbe placed in thesecond stagetreatment afterthe domestictank

Hypochloritetank

Fig. 34 2nd Stage Water Treatment Configuration without Carbon Filter

Bypass lineused when UVsterilizer isserviced

Ultra violetsterilizercontroller

Ultra violetsterilizer

Outlet lineto potablewater tank

Micro filter

Note:The carbonfilter shown infigure 33 couldhave beenplaceddownstream ofthe micro filterand before theUV sterilizer

USECAT1 does not involve only aRWHCAT1 coupled to a WTCAT1but also a monthly bacteriologicaltesting of a water sample takenfrom the potable water tap.

IMPORTANT


63

4.5.aWater treatment equipment sizing

In order to size a water treatmentinstallation for RWH, the majorparameter to consider is water flow. Foroptimum efficiency, it is advised not tooversize equipment, this will not improvewater quality but may rather givenegative results.

Filters selection and sizingFilters are sized based on water flow, asan example let us consider House 1again. The first task consists of sizing thefilters of the primary treatment. We havealready seen that USECAT1 & USECAT2for domestic use as well as USECAT2 forirrigation amount to 105m³ for 5 monthequivalent to 150 days. Consequently theaverage daily consumption is 0.7m³/day.For all purposes a media filter of 1 m³/daywill be selected or the nearest availablesize. The same applies to the cartridgemicron filter.

It is recommended to order the media filter with automaticbackwash for self-cleaning. Indeed, media filters need toget rid of all the pollutants that accumulate inside themedia, this is done by reversing the flow through the mediathus the term backwash. The automatic backwashmechanism avoids the hassle of manual backwash everyother day. The backwash line should be routed to the drain.

Micron filters are not backwashed, the fabric cartridgeinside the filter is simply replaced every six month ordepending on clogging. It is therefore recommended tohave pressure gages across filters to monitor their state ofclogging.

Dosing pumps and chlorination tanksThe hypochlorite tank is filled with water then liquid sodiumhypochlorite solution (15% by weight) is added to reach aconcentration of no more than 3% chlorine (by weight) inthe hypochlorite tank. In order to reach that concentration,fill a 100 liter hypochlorite tank with 80 liters of water and20 liters of sodium hypochlorite solution. Hypochlorite tanksize should be such that one fill should not last for morethan 15 days because chlorine gas goes out of solution.Always use soft water from the RWH tank to fill thehypochlorite tank.

As a rule of thumb, every 1 m³ of treated domestic waterrequires 1 liter of hypochlorite solution at a concentrationof 3% which is the concentration in the hypochlorite tank.Thus if a house consumes 30 m³ of treated domestic waterper month, a 50 liter solution tank is ideal.

Dosing pumps are also selected based on water flow asshown above, these devices come in standard sizes, onesize fits a wide range of water flows. Basically dosing pumpflow is 1 liter/day for every 1 m³/day of treated water alwaysbased on a 3% solution tank concentration.

UV sterilizers These also are sized based on flow, UV-C radiation doseshould be no less than 40 mj/cm2 according to class Arequirements of the ANSI/NSF standard 55 (ref:23).

Filtration will assist in theprevention of discoloration ofplumbing fixtures and is asafeguard against small debris orsediment entering the toilet valves,thus maintaining proper function.

Filtration removes turbidity(cloudiness) which interferes withdisinfection.

HINTSTO CONSIDER


64

4.5.b Water treatment equipment materials

Always use first quality equipment from renownedmanufacturers in what relates to water treatment. In order toassure that filters do not leach undesirable contaminants intothe water, use filtration systems that have been certified to meetANSI/NSF Standard 61 requirements (ref:23).

Use sodium hypochlorite compounds that are certified inaccordance with ANSI/NSF Standard 60 requirements (ref:23).


Table 18.Treatment Techniques

Location

Drains, gutters and downspouts

Within Tank

Before tankAfter pumpAfter chlorination

Within Tank or at pump(liquid or granule), before activatedcharcoal filter

After activated charcoal and carbonfilters, before storage/tap

Method

SCREENINGLeaf screens andstrainers

SETTLINGSedimentation

FILTERINGFirst Flush divertersSand filterCarbonFilter/Activatedcharcoal

DISINFECTINGChemicaltreatment/ChlorineUltraviolet light

Result

Prevent leaves and otherdebris from entering tank

Settles out particulatematter

Reduces suspendedmaterialSieves sedimentRemoves chlorine, odors,hydrocarbons, improves taste

Kills microorganisms

Kills microorganisms

WAT

ER T

REAT

MEN

T

Avoid products that contain fragrancesand UV stabilizers. Most specifically donot use chlorine compounds designedfor use in swimming pools as theseproducts often contain cyanide based UVstabilizers. This guideline does notrecommend the use of calciumhypochlorite compounds because it isless stable and may result in maintenanceand storage problems.


65

4.6 Pumps

Pumps are used to move fluids andimpart to them the necessary pressurerequired in any given process. They are ofdifferent types and models, In RWHSpumps are vital, therefore a goodunderstanding of the different kindsinvolved, their functioning and how toselect them is very important. Basically apump for the purpose of this guideline ismade of two parts, the pump itself thatimparts movement to the fluid and theelectric motor that drives the pump.

A pump is characterized by two majoroperating parameters namely the flowand the head. The flow as the nameimplies is the quantity of water handledby the pump per unit time, it isexpressed usually as liters/sec or m³/hr.The head represents the pressure thatcould be developed by the pump, it isexpressed as Bars or height in meters ofwater. 1 bar is equivalent to thepressure at the bottom of a column ofwater 10 meters high. Therefore 1 baris equivalent to 10 meters head.

Submersible pumpsAs the name implies, these pumps areimmersed in the water usually when thestorage tank is underground making itdifficult to have a side intake. Two kindsof submersible pumps are encountered,the submersible well pump and thesubmersible pit pump.

Below, is a picture of a submersible wellpump showing its main components. Asthe name implies this type of pump isusually installed in wells which are of

small diameter therefore the water passes along the motor andcools it before entering the pump intake. In case a well pump isto be used in a RWH storage reservoir, then it has to be installedhorizontally at the bottom of the tank otherwise much of thestorage reservoir volume cannot be pumped and second itneeds to have a sleeve around the motor, open only on themotor end to force the water to enter the sleeve and cool themotor. Actually the sleeve replaces the well. It is preferable toconnect the open end of the sleeve to a floating suction intaketo prevent the suction of dirt from the tank bottom.

The other type of submersible pump is the submersible pitpump, as the name implies it is installed in a pit. It does not needa sleeve as it is designed to operate in a tank however its onlydrawback is that it can generate much less pressure than asubmersible well pump and the suction could draw dirt fromthe tank bottom as it is practically impossible to fit the pumpwith a floating suction intake. However this issue may beovercome if the pump is installed on a slightly elevated pad.

Both configurations need careful design and to devise practicalways to pull them out of the tank in case repair or maintenanceis required while the tank may be full. A definite advantage ofsubmersibles is that they are noiseless.

Fig. 35 Submersible Pumps

Pump discharge

Pumpbody

PumpIntake

ElectricMotor

Pump discharge

ElectricMotor

Pumpbody

PumpIntake


66

Booster set: It is an assembly made of one(simplex), two (duplex) or three(triplex) booster pumps equippedwith a pressure tank and pressureswitch to actuate the pumps upon offall in pressure in the pipework.Booster sets usually supply water toend users so that supply pressureremains fairly constant. This may avoidthe unpleasant experience of reducedflow under a shower if other toilets arebeing used when the network has un-sufficient pressure.

(Fig.38) shows a duplex booster setcomplete with a skid rail (below thepumps), the pumps, the stainless steelsuction manifold that feed the pumpswith water, the pressure actuatedvariable speed drivers (black boxesabove the pumps) and the dischargemanifold to which the pressure switch(grey) and pressure tank (red) areconnected.

Booster PumpsThese are installed external to the tank usually in a mechanical roomor an enclosure pit to protect them from the weather and dampenthe noise. As fig 36 below shows, booster pumps consist of an electricmotor and a pump body. These pumps are also called end suctionpumps because they draw water from one end of the pump.

Booster pumps have a wide range of operating characteristics asfar as flow and pressure, they are simple to install and servicebut the drawback is the possible noisy operation if installednearby living quarters.


Fig. 36 Duplex Submersible Pit Pumps

Fig. 37 Horizontal Booster Pump Fig. 38 Duplex Booster set

Float switch forsubmersiblepump operation

Submersiblepump

High level alarmfloat switch

Pump body

Pumpsuction

Pumpdischarge

Check valve

Electric motor

Pressure tank

Suctionmanifold

BoosterPumps

Pressureswitch

Dischargemanifold

Variablespeedcontrollers


67

Pressure tanks and switchesPressure switches activate the controlsthat activate the pump to meet thedemand. The size of the pressure tankdetermines whether your systemoperates efficiently and effectively. Therule of thumb for sizing a pressure tank isthree times the liters/minute of thepump equals the liter size of the pressuretank. Thus if a pump delivers60 liters/minute the pressure tank sizewill be 180 liters.

Pump protectionShould your rainwater cistern becomelow on water, it will be essential that thepump is protected from running whilethere is not sufficient water for the pumpto function. If the pump continues to runwithout sufficient water, the pump will bedamaged. A simple float switch in therainwater cistern will protect the pumpfrom running when the water leveldeclines. A float switch automaticallyresets when the tank refills.

A check valve should be installed at thepump discharge to avoid water backflowwhich may also damage the pump andempty the discharge line.

In order to protect the pump from erosionand possible jams resulting from fairly bigsolid particles entrained in the water likerust flakes, small wood pieces, plastics,small pieces of cloth, etc. a strainer shouldbe installed at the pump suction intake.

Flexible connectors should be installed atsuction and discharge connections of pumpto minimize vibration and noise transmissionthrough piping especially if it is steel.

Floating suction intake strainerTo aspirate the water from the tank, a floating intake strainer islocated at the end of the pump’s suction hose. Sediment,bacteria and other pollutants generally settle to the bottom ofthe tank, with concentrations of pollutants higher at the bottomthan at the surface of the water. Studies have also shown thatbacteria levels can be higher at the surface of the cistern waterthan elsewhere in the tank (ref:23). To avoid these two areas ofconcern, the floating filter takes water from the tank a fewcentimeters below the water surface. Floating suction intakestrainers seldom clog, they should be made of high-qualitystainless steel.

Fig. 39 Booster pump connection details

Dismantlingunion

Check valve

Strainer

Flexibleconnectorat suctionside

Flexibleconnectorat dischargeside

PUMPS ARE USED TOMOVE FLUIDS ANDIMPART TO THEM THENECESSARY PRESSUREREQUIRED IN ANYGIVEN PROCESS


68

pump centerline and the pipeworkdischarge into the elevated tankexpressed in meters.

- The friction between the water in thepipe and the pipe walls which the pumpneeds to overcome. This frictionresistance is also expressed in metersand can be computed once the pipesize, pipe length, pipe type and flow aregiven. It is expressed as Hf.

- The head required to operate any end ofline device like an automatic valve, a ballvalve, etc. in our case we have none. It isexpressed as Ha.

4.6.a Pump sizing

Pumps are sized using two main parameters, flow andHead. Flow depends on water demand while Headdepends on the characteristics of the project like buildingelevation, distance between storage tank and point of use,type of water treatment equipment, etc.

A rainwater harvesting system network may involve morethan one type of pump, therefore each pumping functionwill be discussed here below.

Starting with the most basic function, namely pumpingwater from the underground storage tank to a roof tank.Taking House1 as example, we have seen previously thatthe daily water demand is around 0.75 m³/day. Thus thepump needs to raise daily that amount to the roof. But inpractice the roof tank may be around 2 m³ to allow sparereserve for two days in case of a malfunction. If we assumethat the pump needs to fill the roof tank in one hour timethen the flow will be Q = 2 m³/hr, which is a fairly smallpump. Having determined the flow, it is now time tocompute the head.

(Fig. 40) Below gives a good representation of a widelyused installation for lifting water to a higher level from anunderground reservoir. The pump is located above the tankand is equipped with a suction line terminated with a footvalve. That valve could be of the floating type.

The head of the pump is the summation of several factors:

- The vertical distance between the pump centerline andthe underground tank water surface, the pump needs to“lift” the water over that distance. Usually it is assumedthe pump operates in worst case conditions (i.e: an emptytank) thus it is practically distance A expressed in meters.

- The vertical distance the pump needs to push the water,which in worst case conditions is height E between the


PUMPS ARE SIZEDUSING TWO MAINPARAMETERS, FLOWAND HEAD.

FLOW DEPENDS ONWATER DEMAND WHILEHEAD DEPENDS ON THECHARACTERISTICS OFTHE PROJECT


69

6

Fig. 40A Reservoir with float strainer in submerged suction configuration Fig. 40B Reservoir with float strainer in suction lift configuration

Fig. 40C Reservoir with float strainer in submersible well pump configuration Fig. 40D Reservoir with float strainer in submersible pit pump configuration

Fig. 40 Underground Reservoir pipework to roof tank in suction lift configuration

Pump

UGA

B C

D

E

20

Float Float StrainerStrainer Flexible Hose

Pipe External PumpAdjacent toTank

Pipe

Elbow

External PumpFlexible Hose

Float Motor

FlexibleHose

StrainerCoolingJacket

Pipe

Pump

20cm 15cmConcrete Pad

Pipe Motor

Pump

PumpIntake


70

Note that hf takes into considerationfittings losses

Therefore TDH = 2.5 + 18 + 5.7 = 26.2mto be rounded to 27 m

Our pump can now be specified as abooster pump having a flow Q = 2 m³/hrat a TDH = 27 m.

Exactly the same calculations wouldapply for all pumps configurations exceptthat one needs to pay attention to thesign of “A”

Suppose now that the circuit above goesthrough a filtration unit consisting of amedia filter and a micro filter. The pressuredrop through the media filter is 0.5 barswhen clogged and that of the micro filter is0.6 bars. Both of them will have an Ha =11 meters. The pipework length increasesfrom 30 to 45m because it has to be routedto the mechanical room.

Therefore

Hf = 45*0.1913 = 8.6 m

T.D.H = 2.5 + 18 + 8.6 + 11 = 40.1 m tobe rounded to 41 m

Our pump can now be specified as abooster pump having a flow Q = 2 m³/hrat a TDH = 41 m.

Another application to consider is whena booster set feeds water to the buildingas shown in (fig.41) below. The pumpfeeds the domestic water networkhowever the Jacuzzi which is two floorsbelow requires 2 bar (the equivalent of20 m water column) for its operation.

The Total Discharge Head (TDH) of the pump his expressed as:

T.D.H = A + E + Hf + Ha.

A and E are fairly easy to determine, they can be measured fromdrawings or site. It is important to note that A could be positiveor negative depending on the type of configuration. Inconfigurations 40A, 40C and 40D A is negative while inconfigurations 40 and 40B A is positive. Note that inconfigurations 40 and 40B, A should never exceed 3 meters asthe pump may lose its prime and get damaged.

Hf is the product of the pipe friction factor hf determined fromAnnex E and the overall pipe length. In our case the overall pipelength L = A + B + C + E + D.

Thus Hf = hf*L

Ha in our case = 0

Assume A = 2.5 meters, B = 2 meters, C = 4 meters, E = 18meters, D = 3.5 meters.

Then, L = 30 meters.

To find hf follow the steps below

- If pipe is exposed or buried, opt for a galvanized steel type. Ifpipe is protected in a shaft then PPR or PEX is acceptable.Suppose in our case pipe is exposed thus requiring theselection of a Galvanized Steel Pipe (GSP).

- Using the Table in Annex E select pipe size using the hourlyflow determined above (Q = 2 m³/hr and type of pipedetermined in the previous step (GSP). The friction factor hfcan also be determined. In our case pipe diameter is ½ inchand hf = 0.038871

we specify the pipe as GSP, sched 40, Ø = 3/4 inch

Q = 2 m³/hr

hf is found to be = 0.1913 then Hf = 30*0.1913 = 5.7 meters.



71

• Pump systems should be designed to meet the expected peakdemand

• Pumps drawing water from the underwater storage tankshould have their intake just below the water surface using afloating intake strainer

• Pumps should not have a suction lift exceeding 3 meters

• Pumps should always have low level cut off to protect themfrom dry running

• Never oversize pumps, pumps should always operate at theirbest duty pump

• Always choose pumps from well-known manufacturers

• Pumps should be preferably all stainlesssteel 316 construction

HINTS TO CONSIDER

4.6.b Pump MaterialApart from the electric motor, pumps consist mainly of twocomponents, the pump casing and the impeller. The materialof construction of the casing and impeller greatly affect thedurability and proper operation of the pump. Pump casingscould be made of cast iron or 316 stainless steel sheetsstampings while the impeller could be bronze, stainless steelstampings or Noryl.

For submersible and booster pumps, it is recommended tochoose an all 316 stainless steel construction for all pumpsapplications related to rainwater. Whenever possible chose alow speed pump 1500 rpm instead of a high speed 3000 rpm,however the pump flow and head may dictate a 3000 rpmpump. Always purchase pumps from well-knownmanufacturers.

Pumps should always be protected against dry running withlow level cut off float switches.

PressureTank

Booster System

Jacuzzi

8 m

In this case the pump is not lifting water butrather delivering water to lower floors. In thiscase the TDH could be written as

TDH = -8 + Hf + Ha

Where Ha = 2 bars or 20 m head. (-8 is thenegative head between the pump and thefixture for which the pressure calculationsare required). Whenever the load is belowthe pump, the lift is negative.

The pump flow requirement is 0.7 m³/dayor 0.2 m³/hr. To convert from average dailyflow to hourly peak flow divide daily flow by4 in order for the pump to meet peakdemand.

Pipe length L = 8 m, considering PPR pipe Ø20mm, hf = 0.04 for Q = 0.2 m³/hr as perAnnex E.

Consequently TDH = -8 + 8*0.04 + 20 ~ 12 m

Therefore a duplex booster set with pumpcharacteristics Q = 0.2m³/hr and TDH = 12m is to be ordered. The booster set shouldhave an expansion tank of 12 liters.

Fig. 41 Booster Set feeding the building network

2 BAR Requirement


72

Careful preventive maintenance by theowner or operator is the best way toassure long trouble free life for theequipment and the highest level of waterquality. Common sense and soundinstallation practices should prevail.

The following maintenance practices arerecommended;

• Every 3 years or less

- Clean all tanks, disinfect and flush.- Check inner surfaces plaster lining of

concrete tanks. If necessary repairlining if cracked or peeling and paintagain using appropriate paint.

- Check submersible pumps in tanks forapparent damage, rust, inlet coggingor damaged electrical cable.

- Change water treatment filter mediaif recommended by supplier.

- Change UV lamp as per manufacturerrecommendation.

• Every year before rainy season check the following

- Gutters and drains are not obstructed.- No polluting objects on catchment surfaces (dead birds or

rodents, organic waste, etc.).- First flush tank is clear of debris and cleaned.- Strainer of first flush tank is not damaged, if torn or cracked

replace.- Tree branches and any vegetation that interferes with the

gutters or overhangs RWHCAT1 roofs should be pruned.

• After first rain event that lasts more than 30 minutes

- Clean strainer of first flush tank.- Clean sump of first flush tank, make sure drain pipe is not

clogged.

• After each torrential rain event

- Clean strainer of first flush tank.- Clean sump of first flush tank, make sure drain pipe is not

clogged.

• On a 6 month basis

- Check cartridge filter of micro filter and replace if clogged.

- Clean inner part of micro filter housing.

- Check UV lamp operation as per manufacturer instructions,replace if necessary.

- Check high/low level alarm float switches operation byoperating manually.

- Check validity of hypochlorite chemicals that are in stock.Hypochlorite chemicals should not be kept in store for morethan one year.

- Check validity of fire extinguishers.


MAINTENANCE 5

CAREFUL PREVENTIVEMAINTENANC IS THEBEST WAY TO ASSURELONG TROUBLE FREELIFE FOR THEEQUIPMENT


73

• On a regular basis check the following

- Pumps for abnormal noises orvibrations.

- Any leakage from pipes or aboveground tanks.

- Control panels for burned out lamps.- Liquid level in hypochlorite tanks.- Clogging of filters.- Pressure tank gas charge. - Booster system operation, if booster

system is hunting this may mean thatpressure tank diaphragm is damagedor pressure tank lost its gas charge.

- Water quality. USECAT1 water shouldbe tested at the tap on a fortnightbasis or at most monthly basis.

- Hypochlorite chemicals are notexposed to the sun.

- Technical rooms are clean and welllighted.

- Replace burned light bulbs.- Quickly wash with abundant water

any spill of hypochlorite on your skin. - Exit lights are properly functioning.- As a general rule, the cleaner the water

going into the cistern, the higher thewater quality and the better the system’soverall performance will be.

- Maintenance of the UV light involvescleaning of the quartz sleeve and thebulb itself. Some UV lights aredesigned with an integral wiper unit.Again, follow the manufacturer’sinstructions and recommendations.

Efficient water use practices- Close water taps when not used

- Dripping taps should be repaired

- Use water efficient faucets, plumbing fixtures and washingmachines

- Use plants and shrubberies adapted to the local weather, itis strongly advised not to plant gazon

- It is strongly advised not to have a swimming pool or awater pond in single family residences

- Do not rinse floors with water, use mops

- Adopt dual plumbing circuits for grey water use

Safety and Health

- Always wear goggles, gloves and dust masks when fillinghypochlorite tanks

- Wash with abundant water any part of the body that camein contact with hypochlorite

- Always shut off power on equipment being serviced

- Keep an operating fire extinguisher in the technical room

- Keep a first aid kit in a prominent location in or nearby thetechnical room

- Post in a prominent place the contact numbers of theneatest medical care center, the red- cross and civildefense

- Make sure technical room floors are always dry and notslippery and objects are not lying on the floor

- Make sure technical rooms are well lighted

- Always use the proper tools for the job

- Use gloves, goggles and ear plugs when using grinder


GLOSSARY

National guideline chapter grossery and references.qxp_Layout 1 1/25/17 4:16 PM Page 74

75

A device located at the bottom of a storage tank that permits water to enter astorage tank with minimal disturbance to particles that may have settled to thebottom of the tank.

Area from which rainwater is collected to be used in a rainwater harvesting system(e.g. roof area).

Refers to the International Plumbing Code.

A screen or other device installed to prevent the accumulation of leaves, needles,or other debris in the system.

Reduction of viable microorganisms to a level that is deemed suitable for theintended applications. Typical units of measure are Colony Forming Units per100ml liter (cfu/100ml).

Water for household and commercial areas of use that does not have to have thequality of drinking water.

Collect run off water, they are used mainly for flat surfaces like a flat roof, a terraceor driveway.

System for protecting the water pump against running when no water is present.

Physical removal of liquid-born contaminants by means of separation from theoutput flow. Particulate filtration removes suspended particles, measured in unitsof total suspended solids (TSS), while other forms of filtration, such ascarbon/absorption filtration, removes dissolved compounds measured in unitsof total dissolved solids (TDS).

A device or method for removal of debris from collection surface by divertinginitial rainfall from entry into the cistern / tank.

Having a slope no greater than 1 in 50.

Naturally occurring water on the Earth’s surface; in ice sheets, ice caps, glaciers,icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwaterin aquifers and underground streams. Fresh water is generally characterized byhaving low concentrations of dissolved salts and other total dissolved solids.Water that infiltrates into the ground and no longer flows across the surface.

CALMING INLET

CATCHMENTSURFACE AREA

CODE

DEBRIS EXCLUDER

DISINFECTION (STERELIZATION)

DOMESTIC WATER

DRAIN

DRY RUNNING PROTECTION

FILTRATION

FIRST FLUSH TANK

FLAT

FRESH WATER



The effluent from lavatories, showers and bathtubs only. WC, washing machines,dish washers, kitchen sink and other plumbing fixtures must not be part of thegrey water network.

Water that infiltrates into the ground and no longer flows across the surface.

A channel at the eaves or a collector on the sloped roof of a building, for carryingoff rainwater.

Rainwater that is collected in the cistern / tank.

Element in the ground that is filled with gravel, ballast or special non-permeableplastic elements and that stores rainwater that is fed into it on an intermediatebasis before the water evaporates into the atmosphere or seeps into thesurrounding soil.

Drains are connected to leaders or pipes that convey the water to the storagetank.

Residual water volume that is constrained by the process in which neithersediment nor scum can be sucked in for the protection of the pump.

The highest level that water in a cistern can rise before flowing out of the tank.

Line for leading excess rainwater away when the cistern is full.

Pipes that convey the harvested rainwater and distribute it to various fixtures.

Characteristics of a precipitation event (e.g. intensity, duration).

Water collected from runoff of roofs or other structures after a rain event.

Water system for utilizing rainwater, consisting of a cistern/tank, pipe, fittings,pumps and/or other plumbing appurtenances, required for and/or used toharvest and distribute rainwater.

Useful water volume (water inflow) determined over a certain period of time.

A section of pipe with a 180-degree bend.

GREY WATER

GROUND WATER

GUTTER

HARVESTED WATER

INFILTRATION FIELD

LEADER / DOWNSPOUT

MINIMUM WATERVOLUME

OVERFLOW LEVEL

OVERFLOW LINE

PIPING SYSTEM

PRECIPITATIONCHARACTERISTICS

RAINWATER

RAINWATER HARVESTING SYSTEM

RAINWATER YIELD

RETURN ELBOW


77

A system, comprised of roof drains, overflow drains, scuppers, gutters and downspouts, used to convey the rainwater from the roof surface to the tank/cistern.

A filtration device, constructed of corrosion resistant wire or other mesh, havingopenings in determined areas.

Separation of solids from the water via gravity.

It is the slotted surface where water enters the drain.

Pressure needed to deliver water to the designated fixtures.

Having a slope greater than 1 in 50.

A method of providing water to plants by raising the water table to the root zoneof the crop or by carrying moisture to the root zone by perforated undergroundpipe. Also known as subirrigation.

Application of water to the soil by means of pipes or furrows along the surface.

Any rainwater that touches the ground and flows across the surface of the ground(roadway, parking surface, gully, creeks, streams, etc.).

Pressure needed to deliver water to the designated fixtures.

The central water storage component of the rainwater harvesting system.Protection and maintenance of the tank is essential for the health of the system.

Element in the ground that is filled with gravel, ballast or special permeable plasticelements and that stores rainwater that is fed into it on an intermediate basisbefore the water seeps into the surrounding soil.

Amount of rain, expressed as the water height in millimeters over a horizontalarea for a span of time under consideration.

Volume that can be completely used during operation (typically 80 – 90% ofstorage volume).

ROOF DRAINAGE SYSTEM

SCREEN

SEDIMENTATION

STRAINER

SYSTEM PRESSURE

SLOPED / GABLED ROOF

SUB-SURFACEIRRIGATION

SURFACE IRRIGATION

SURFACE WATER

SYSTEM PRESSURE

TANK / CISTERN

TRANSPIRATION FIELD

QUANTITY OFPRECIPITATION

USEFUL VOLUME


REFERENCES


79

1- Shiklomanov and Rodda (2003) ISBN: 0 521 82085 5.

2- Falkenmark and Lindh 1976, quoted in UNEP/WMO. “Climate Change 2001:Working Group II: Impacts, Adaptation and Vulnerability”. UNEP.

3- Lebanon’s Second National Communication to the UNFCCC, MOE, UNDP, 2011.

4- National Physical Master Plan for the Lebanese Territory, NPMPLT, Final report, Dec2005.

5- Schema directeur hydroelectrique du Liban, phase 2, MEW, 2012.

6- National Water Sector Strategy (NWSS), Ministry of Energy and Water (MEW), 2010.

7- Central Administration of Statistics (CAS), demographic report 2007 (in Arabic)page 135 Table 7.a (in English).

8- International Plumbing Code (IPC), International Code Council, 2006.

9- Basic Principles For The Design of Centrifugal Pump Installations, Sihi – Halbero.

10- Water Resources In Lebanon - Country Paper, ESCWA, Regional Symposium OnWater Use And Conservation, Bassam Jaber, 1993.

11- Water Treatment Handbook, Fifth Edition, Degremont, 1979.

12- Engineering Data Book, First Edition, Hydraulic Institute.

13- Etude Hydro-Pluviometrique Comparative Des Bassins Versants De La RegionCotiere Intermediaire Du Liban, Publication De L’Universite Libanaise, ZoubeidaTayara, 1998.

14- State and Trends of the Lebanese Environment, ‘STLE’, UNDP / Ministry OfEnvironment (MOE), 2010.

15- Building law 646 dated 11/12/2004.

16- Building law implementation decree 15873.

17- Environment Protection Law, 444 dated 29/7/2002.



18- Potable water standard, decree 1039 dated 2/8/1999.

19- JICA Study, Water Resources Management Master Plan in Lebanon, 2003.

20- Acid Rain and Chemical Composition of Rainwater in Lebanon, AmericanUniversity of Beirut, Master’s thesis, Nadine Habib Aoun, 2007.

21- Roof Rainwater Harvesting Systems for Household Water Supply in Jordan, ScienceDirect, Fayez A. Abdulla*, A.W. Al-Shareef, 2008.

22- Civil Aviation Meteorological Reports, Ministry of Transportation and Public Works(MTPW), 2011.

23- National Science Foundation (NSF) - Protocol P151, NSF International, 1995.

24- Georgia Rainwater Harvesting Guidelines, 2009.

25- Ontario Guidelines for Residential Rainwater Harvesting Systems, 2010.

26- The Texas Manual on Rainwater Harvesting, 2005.

27- ��

28- ��

, e©∏ƒeÉä, eæû°ƒQGä {Gdù°Ø«ôz, dÑæÉ¿ hKôhJ¬ GdªÉF«qá, YóO911.

, Od«π GdªæÉW≥ Gd∏ÑæÉf«qá, eójôjqá Gdû°ƒDh¿ Gdé¨ôGa«qá a» Gdé«û¢ Gd∏ÑæÉf», fÉXº f©ª¬.

2013

2012


ANNEXES

ANNEXE A

ANNEXE B

ANNEXE C

ANNEXE D

ANNEXE E

ANNEXE F

ANNEXE G

ANNEXE H



ANNEX A RAINFALL DATA FOR LEBANESE LOCALITIES

Annexe.qxp_Layout 1 1/25/17 4:27 PM Page 82

83

RAINFALL DATA FOR LEBANESE LOCALITIES CONT’D


85



87



89



91



93



95



97



99



100National guideline f o r r a i n w a t e rharvesting systems



101



103



105



107



109

ANNEX BLIST OF METEOROLOGICAL STATIONS

Station Name BEYROUTH-GOLF HOUCH-El-OUMARA_ZAHLE DAHR EL BAIDAR AL ARZ-LES CEDRES RAYAK- AMARA EL ABDE SOUR ZAHRANI EL QLAIAAT-AKKAR EL QOUBAYAT QARTABA EL QOUSSAIBAH-Ksaibe BAYSSOUR JEZZIN FAQRA EL HERMEL DEIR-EL-AHMAR EL QARAOUN-BARRAGE MARJAYOUNTRIPOLI- BOUEE ZAHRANI- BOUEE BEYROUTH- BOUEE BALAMANDSYR-ED-DENNIYEKAFAR CHAKHNAKASLIK JOUNIEHDEIR-EL-KAMARBAROUK FRAIDISSAIDALEBAAEL QUASMIYEEL_QAAKAFAR QOUQ / RACHAYATANNOURINEKAFAR DOUNINEEL MESHREFBeirut International AirportTRIPOLI_IPCHEMLAYADOURIS

Altitude14926151618918523741054971222584940107016556059438438270003599262604179411141433195131205183856039512.358051009

Mouhafaza BeirutBekaaBekaaNorthBekaaNorthSouthSouthNorthNorthMount LebanonMount LebanonMount LebanonSouthMount LebanonBekaaBekaaBekaaNabatiyeNorthSouthBeirutNorthNorthNorthMount LebanonMount LebanonMount LebanonSouthSouthSouthBekaaBekaaNorthNabatiyeMount LebanonMount LebanonNorthMount LebanonBekaa

CazaBeirutZahleZahleBcharreZahleAkkarSourSaidaAkkarAkkarJbeilBaabdaAleyJezzineKesrouanHermelBaalbekWest BekaaMarjayounTripoliSaidaBeirutKouraMinieh-DinniehZghartaKesrouanChoufChoufSaidaJezzineSourHermelRachayaBatrounBent JbeilChoufBaabdaTripoliMetnBaalbek



ANNEX CPOTABLE WATER STANDARDS DECREE 1039/1999:161

Chemical name - Chemical symbolChlorine (CL2)pH value Total dissolved solids (TDS)Copper - cu Iron - Fe Magnesium - Mg Manganese - Mn Sulfates - SO4 Zinc - Zn Calcium as CaCO3 Chlorides - CL Total Hardness as CaCO3Phenolic compounds as Phenol except naturalPhenols that do not react with Chlore Mineral oils Chloroform extract on coal (carbon) Effective surface factors(Kipritonat Alkyl-Benzene) Ammonia Phosphate - P2O5 Organic material Nitrite - NO2 Hydrogen Sulfide H2SNitrate - NO3 Sodium - Na Potassium - K Aluminum - Al Arsenic - As Cadmium - Cd Cyanide - Cn Mercury - Hg Selenium - Se Lead - Pb Hexavalent chromium - Cr Barium - Ba Silver - Ag Nickel - Ni

Max allowed concentration (mg/L)0.35.6 – 5.850010.3500.0525052002002500.001

None5.0none

none15.00.050.055150120.20.050.0050.050.0010.010.010.050.50.010.02

1. Chemical & Physical properties for Potable (drinking water) - Max concentration


111

Aromatic Hydrocarbons:Fluoranthene 3.4 Benzflorantin11.12 Benzflorantin 3.4 Benzopyrene 1.12 Benzipirilin Alandino (1, 2.3, c, d) pyrene Fluoride between 8 & 12 deg C25 & 30 deg C Halogenated organic compounds Chloroform Dieldrin Lindane Methoxy Chlor Toxaphene 2.4 binary acid summarize Klorvinnox 2 (2, 4.5) tri Klorvinnox

0.00020.0002 & 0.00020.0001 combined 0.00010.00020.00021.50.70.060.10.000020.00020.020.0030.030.009

2. Microbial properties in drinking water

CharacteristicsTotal ColiformsStreptococcus faecalisAnaerobies sporules – Sporulaed sulphite /reducing anaerobesFeacal colifrmEsherichia coliPseudomonas aeruginosaThe total number of microorganisms attemperatures 22 degree for 72 hours37 degree for 24 hours

Max allowed0 in 100 mm0 in 250 mm0 in 50 mm

0 in 250 mm0 in 250 mm0 in 250 mm100 in 1mm

20 in 1 mm



DEMAND TYPE

Drinking, Cooking Residential

Domestic Normal Residential

Domestic Saving Residential

Domestic Normal Hospital

Domestic Saving Hospital

Domestic Normal Hotel

Domestic Saving Hotel

Domestic Normal School

Domestic Saving School

Domestic Normal Jail

Domestic Saving Jail

Domestic Normal Office Building

Domestic Saving Office Building

Domestic Normal Public Building

Domestic Saving Public Building

Domestic Car Wash

Irrigation Hose Green Lawn

Irrigation Sprinkler Green Lawn


Irrigation Hose Shrubbery & Trees



Laundry, WC Normal, Residential

Laundry, WC Saving Residential

Laundry, WC Normal, Hospital

Laundry, WC Saving Hospital

Laundry, WC Normal, Hotel

Laundry, WC Saving Hotel

WC Normal, School

WC Saving School

Laundry, WC Normal, Jail

Laundry, WC Saving Jail

WC Normal, Office Building

WC Saving Office Building

WC Normal, Public Building

WC Saving Public Building


Irrigation Drip Shrubbery and Trees

CATEGORY

USECAT1

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT2

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USE TYPE

NA DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

CAR WASH

IRRIGATION

IRRIGATION

IRRIGATION

IRRIGATION

IRRIGATION

IRRIGATION

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

IRRIGATION

IRRIGATION

PLANTS

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA GREEN LAWN

GREEN LAWN

GREEN LAWN

SHRUBBERY

SHRUBBERY

SHRUBBERY

NA NA NA NA NA NA NA NA NA NA NA NA NA NA GREEN LAWN

SHRUBBERY

IRRIG. TYPE

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA HOSE

SPRINKLER

SUB-SURFACE

HOSE

DRIP

SUB-SURFACE

NA NA NA NA NA NA NA NA NA NA NA NA NA NA SUB-SURFACE

DRIP

USE MODE

NA NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NA NA NA NA NA NA NA NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NA NA

PLUMBING

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

PLUM

BING

2CL

NA NA

CONSUMPTION

3 140

85 70 45 100

70 20 15 50 35 15 10 3 2 30 9 7 5 3 1.5

1 40 26 50 35 50 35 5 3 30 20 10 7 3 2 5 1.5

UNITS

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/cw/m

l/m²/d

l/m²/d

l/m²/d

l/s/d

l/s/d

l/s/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/m²/d

l/s/d

APPLICATION

NA RESIDENTIAL

RESIDENTIAL

HOSPITAL

HOSPITAL

HOTEL

HOTEL

SCHO

OLSCHO

OLJAIL

JAIL

OFFICE BLDG

OFFICE BLDG

PUBLIC BLDG

PUBLIC BLDG

NA NA NA NA NA NA NA RESIDENTIAL

RESIDENTIAL

HOSPITAL

HOSPITAL

HOTEL

HOTEL

SCHO

OLSCHO

OLJAIL

JAIL

OFFICE BLDG

OFFICE BLDG

PUBLIC BLDG

PUBLIC BLDG

NA NA

ANNEX DWATER DEMAND CATEGORIZATION


113

WATER DEMAND CATEGORIZATION (CONT’D)

DEMAND TYPE

Irrigation Drip Shrubbery and Trees

WC Normal, Residential

WC Saving Residential

WC Normal, Hospital

WC Saving Hospital

WC Normal, Hotel

WC Saving Hotel

WC Normal, School

WC Saving School

WC Normal, Jail

WC Saving Jail





Laundry, Normal, Residential

Laundry, Saving Residential

Laundry, Normal, Hospital

Laundry, Saving Hospital

Laundry, Normal, Hotel

Laundry, Saving Hotel

Laundry, Normal, Jail

Laundry,Saving Jail

WC Normal, Residential

WC Saving Residential

WC Normal, Hospital

WC Saving Hospital

WC Normal, Hotel

WC Saving Hotel

WC Normal, School

WC Saving School

WC Normal, Jail

WC Saving Jail





Irrig. BG Green Lawn

Irrig. BG Shrubbery and Trees

CATEGORY

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT3

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USECAT4

USE TYPE

IRRIGATION

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

DOMESTIC

IRRIGATION

IRRIGATION

PLANTS

SHRUBBERY

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA GREEN LAWN

SHRUBBERY

IRRIG. TYPE

SUB-SURFACE

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA SUB SURFACE

SUB SURFACE

USE MODE

NA NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NORM

ALSAVING

NA NA

PLUMBING

NA PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2C1

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2L

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

PLUM

BING

2C2

NA NA

CONSUMPTION

20 15 20 15 20 15 85 70 15 8 70 20 15 50 20 11 30 20 30 20 15 12 20 15 20 15 20 15 5 3 15 8 10 7 3 2 5 1

UNITS

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/p/d

l/m²/d

l/s/d

APPLICATION

NA RESIDENTIAL

RESIDENTIAL

HOSPITAL

HOSPITAL

HOTEL

HOTEL

SCHO

OLSCHO

OLJAIL

JAIL

OFFICE BLDG

OFFICE BLDG

PUBLIC BLDG

PUBLIC BLDG

RESIDENTIAL

RESIDENTIAL

HOSPITAL

HOSPITAL

HOTEL

HOTEL

JAIL

JAIL

RESIDENTIAL

RESIDENTIAL

HOSPITAL

HOSPITAL

HOTEL

HOTEL

SCHO

OLSCHO

OLJAIL

JAIL

OFFICE BLDG

OFFICE BLDG

PUBLIC BLDG

PUBLIC BLDG

NA NA



PPR SCHED 20 PEX SCHED 20 GSP SCHED 40

ANNEX EPIPE SIZES AND FRICTION FACTORS

Q (m³/hr)0.10.20.30.40.50.60.70.80.911.11.21.31.41.51.61.71.81.922.12.22.32.42.52.62.72.82.933.13.23.33.43.5

DN (mm) 2020202020202020202020202525252525323232323232323232323232323232324040

hf

0.00750.03060.06250.10450.15650.21830.28970.37080.46140.56150.67110.79020.29070.33370.37950.42810.47960.15720.17370.19110.20920.22810.24780.26830.28960.31170.33450.35820.38260.40780.43380.46050.48810.16550.1747

DN (mm) 2020202020202020202020252525252525252525253232323232323232323232323232

hf

0.00420.02010.04090.06830.10200.14200.18820.24040.29880.36320.43370.16760.19420.22280.25320.28540.31960.35560.39340.43310.47470.14560.15810.17110.18460.19860.21300.22800.24350.25940.27580.29280.31020.32810.3465

DN (inch) 1/21/21/21/21/21/21/21/21/21/21/21/21/21/23/43/43/43/43/43/43/43/43/43/43/43/43/43/43/43/411111

hf

0.00220.01290.02660.04480.06750.09450.12590.16170.20180.24620.29490.34800.40540.46700.13310.15030.16860.18790.20820.19130.25190.27530.29970.32510.35150.37900.40750.43700.46750.49910.14690.15610.16550.17520.1851


115

PPR SCHED 20 PEX SCHED 20 GSP SCHED 40

Q (m³/hr) 3.63.73.83.944.14.24.34.44.54.64.74.84.955.15.25.35.45.55.65.75.85.966.16.26.36.46.56.66.76.86.97

DN (mm) 4040404040404040404040404040404040404040404040404040505050505050505050

hf

0.18410.19380.20370.21380.22420.23490.24570.25680.26820.27970.29160.30360.31590.32840.34120.35420.36740.38090.39460.40860.42280.43720.45190.46680.48190.49730.16330.16820.17330.17840.18360.18890.19420.19960.2051

DN (mm) 3232323232323240404040404040404040404040404040404040404040404040404040

hf

0.36530.38470.40450.42490.44570.46700.48880.16670.17400.18150.18910.19690.20480.21290.22110.22950.23800.24670.25560.26460.27370.28300.29240.30200.31180.32160.33170.34190.35220.36270.37340.38420.39510.40620.4174

DN (inch) 1111111111111111111 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/41 1/4

hf

0.19540.20590.21660.22770.23900.25060.26240.27460.28700.29960.31260.32580.33930.35300.36700.38130.39590.41070.11290.11690.12100.12520.12940.13370.13810.14250.14700.15160.15620.16090.16570.17060.17550.18050.1855

PIPE SIZES AND FRICTION FACTORS (CONT’D)



ANNEX FFIRST FLUSH TANK DETAILS

X+(2+2)=Cover mm Galvanized Steel TankX+(10+10)=Cover mmConcrete Tank

Cover

Screen Plate

Bottom

X+(2+2) X X

X


117

FIRST FLUSH TANK DETAIL (CONT’D)



ANNEX GPRICING ESTIMATES OF SYSTEM COMPONENTSAS PER DATE; July 2014

Table 1. Storage Tank Material Pricing (July 2014)

Assumptions; Consumption: 2m2/p/d Concrete price: 1m3=250$

RWH System: PE Tank with several chambers within, to include water treatment, of a certain size. (NOT INCLUDED WITHIN THIS STUDY)

Material

Concrete

PE Above Ground

Single layer Tanks

Large Capacity Tanks

Triple Layer Tanks

PE Under Ground

Tanks

Modular

PE with RWH System*

Stainless Steel

Size / Liters

18000

40000

300

2000

22000

80

500

2000

6000

10000

19000

4500

200

Price $

4000

6500

66

209

2750

52

117

347

1296

2145

6600

3100

750

Table 2. Drains Pricing (July 2014)

Roof Drains

Roof drain(Dome Type)

Roof Double drain(Tower Type)

Specifications - PP- Outlet types: side/bottom- Dome cover – prevent large debris- Linked to normal piping

- PP- outlet types: side/bottom- Double drainage- Gravel guard- Linked to normal piping

Price $

70

90


119

Table 3. Gutters/Downspouts Pricing (July 2014)

PipingGutters

Down Risers

MaterialPVC rain gutters – 174mm diam.Additional Components PVC – 4” pipe with 4.3mm thickness

Table 4. Piping Pricing (July 2014)

PipingPPR4m long pipe4m long pipeGalvanized Steel6m long pipe

Source

TurkishGerman

Turkish

Price $/4 or $/6m 20mm 3.36.51/2in14.0

25mm 4.310.03/4in19.0

32mm 8.016.01in30.0

40mm 12.026.01 1/4in37.0

50mm18.040.01 1/2in44.0

2in60.0

Table 5. Pumps Pricing (July 2014)Pumps Horizontalmultistage pump lift pump or booster pump

Verticalmultistage pump lift pump or booster pumpUsed when a high pressure isrequired

Submersiblelifting pump to be installed insidetank (horizontal setup)

Type

0.5 m3/h @ ~30m W.G1 m3/h @ ~30 m W.G2 m3/h @ ~30 m W.G3 m3/h @ ~30 m W.G5 m3/h @ ~30 m W.G

2 m3/h @ ~45 m W.G3 m3/h @ ~45 m W.G5 m3/h @ ~45 m W.G

1 m3/h @ ~30 m W.G2 m3/h @ ~30 m W.G3 m3/h @ ~30 m W.G5 m3/h @ ~30 m W.G

Price $

370370400400680

110712901290

1537160016001720

Picture

Price $/m 8.58.56

PRICING ESTIMATES OF SYSTEM COMPONENTS (CONT’D)



PRICING ESTIMATES OF SYSTEM COMPONENTS (CONT’D)

Table 6. Carbon & Sedimentation Cartridge Pricing (July 2014)

Size Carbon Cartridge Sedimentation Cartridge Body5 micron 0.5 micron 5 micron 0.5 micron

Source US / EUR Chinese US / EUR US / EUR Chinese US / EUR

Price $ 10 in 44 17 70 26 13 30 6620 in 74 35 135 40 20 37 108

Table 7. Ultraviolet Light Pricing (July 2014)

Flow Rate 19 L/min (5gpm) 30 L/min (8gpm) 45 L/min (12gpm) - High flow Price $

Device 600 750 950Light Lamp 100 130 160

Table 8. Chlorination Dosing System Pricing (July 2014)

Size 2-40 m3 / day

Source Spanish 300

Price $ US 500

Table 9. Sand / Carbon Filter Pricing (July 2014)

Sizing according to flow rate

10 gpm / sq ft

Sand Filter Carbon Filter Price $

1100 1250


121

Rainwater is the product of a distillationprocess which is inherent to the naturalcycle of the water. Water evaporates fromthe ground, from water bodies, fromplants, etc. and rises in the atmosphere aswater vapor to form clouds which are thesource of precipitations as rainfall andsnow.

In theory rain should be pure waterdevoid of any chemicals or pollutionbefore reaching the ground, but inpractice this is not the case becauserainwater collects on its way to theground all kinds of chemicals andparticles like dust, pollen, soot etc.present in the atmosphere.

Two major offending gases present in theatmosphere as a result of human andnatural activities are the oxides ofNitrogen and Sulfur (respectively NOxand SOx). Of course there are manyothers but these two gases greatlyinfluence the acidity of the rainwater, amajor chemical property that det waterquality. Upon their dissolution inrainwater, nitrogen oxides gases formnitric acid and sulfur oxides gases formsulfuric acid. These are the culpritsbehind acid rains that wreck-havoc withforests around the world.

In Lebanon Sulfur dioxides result mainly from burning diesel andheavy fuel in industry, electricity power plants, transportation andthe construction sector. Oxides of Nitrogen result mainly from thetransport sector and to a lesser extent from the electricityproduction sector.

ANNEX HTHE CHEMICAL AND BACTERIOLOGICAL CHARACTERISTICSOF RAINWATER

Courtesy Google images

Atmosphere

Precipitation

Abstraction

UnsaturatedZone

Groundwater

Evaporation

Wind

Evaporationover Ocean

The Water Cycle

Sun

GroundwaterFlowOcean

ScreamFlow

Surface

Flow

Infiltration


122

Dust, soot and other particles generated by human activities likeindustry, construction, traffic, etc. are also found in relativelyhigh concentration in the atmosphere above urban andindustrial centers. However a dusty atmosphere can result alsofrom the easterly winds blowing from the Arabian Peninsula andacross the Syrian inland. Many of us experienced the unpleasantsight of a recently washed car that was all muddied by first rainsthat carried the dust from the atmosphere and deposited it onour cars. Another major factor is the influence of the maritimeenvironment; studies have shown that rain fall along coastalregions of the Mediterranean show a marked increase inchlorides, potassium, calcium, magnesium and Sodium.

Therefore we can safely say that there is a direct relationbetween air quality and rainwater quality. Consequentlyrainwater that falls over Beirut or the coastal region where thebulk of the economic activity is concentrated is surely of lesserquality than rainwater that falls at 800meters altitude. This said,predominant winds could carry pollution far away, thus the lowand mid altitudes of the western side of mount Lebanon rangecould suffer from pollutants generated on the coast andentrained by the dominant winds that blow West-South West.

However it is important to put things into perspective, rainwaterthat has not touched the ground even in Beirut has still way lesschemicals than the purest spring water in Lebanon. Moreover,one study carried between October 2005 and April 2006 over28 sites covering the Lebanese territory showed that therainwater acidity varied between 6.6 and 7.7 which is anindication that acid rain is not an issue for Lebanon at leastduring the sampling period.

However once rainwater touches collection surfaces, then itis entirely a different ball game. Probabilities ofbacteriological contamination are very high due to thepresence of droppings, insects, rodents, etc. moreoverchemical pollution may take a more serious turn if traces ofheavy metals deposits are present on collection surfaces inindustrial or heavily congested urban areas.

Therefore location specific collected rainwater quality is morerelated to collection surfaces which are to a far extent directlydependent on air quality and the exposure of such surfaces to


RAINWATERQUALITY IS LARGELYDEPENDENT ONAMBIENT AIRQUALITY ANDGEOGRAPHICALLOCATION.

biological pollution. Thus to give anexample, areas of Beirut were pigeoncommunities are flourishing willinvariantly have rainwater collectionsurfaces with high biologicalcontamination, indeed probably muchhigher than any area in the mountainwere wild life is more flourishing. This willbe also be aggravated by probabledeposits of traces of heavy metals due tocombustion exhaust, aerosols, tireserosion, etc. The same could be said of allareas near heavily polluting industries(cement, carton, chemicals, etc.).

Further contamination and chemicalloading may occur during the storagephase depending on the type of storagereservoirs and their cleanliness.


CASESTUDIES

Though rainwater harvesting existedhistorically, it is not a commonly usedsystem in Lebanon nowadays. Someindividuals and institutions within thecountry have adopted rainwaterharvesting practices for a variety ofreasons, mainly due to weatherchanges, lack of rain and water scarcity.The following will cover examples ofactual rainwater harvesting systemslocated in Lebanon, including whyrainwater harvesting was chosen, designchallenges and the benefits of utilizingrainwater harvesting on the site.

These cases do not reflect the bestpractices for RWH, treatment and use,but surely show the possible positiveimpact that rainwater collection wouldhave on water supply & demand, waterquality and the environment.

CASE STUDY # 1A PUBLIC SCHOOL

CASE STUDY # 2A MULTI-DISCIPLINARY CENTER

CASE STUDY # 3A PRIVATE SCHOOL

CASE STUDY # 4 RESIDENTIAL BUILDING

CASE STUDY # 5SOS VILLAGE



CASE STUDY # 1A PUBLIC SCHOOL

PROJECT: ISKANDAR RIZK PUBLIC SCHOOL

LOCATION: ACHKOUT – KASERWAN (CAZA) – MOUNT LEBANON (MOUHAFAZA)

ALTITUDE: 1000 m

APPLICATION: STUDENTS TOILETS FLUSHING, TEACHERS TOILETS FAUCETS ANDFLUSHING, CLEANING

SYSTEM: 2 ABOVEGROUND PE TANKS 22,000 X 2 = 44,000L TO CONTAIN THERAINWATER, TREATMENT PLANT FOR DOMESTIC USE, 1 PE TANK = 22,000LTO CONTAIN THE TREATED WATER

CATCHMENT AREA: EXTERNAL PLAYGROUND RARELY USED BY CHILDREN, CONCRETE FLOORAREA OF 690 m2

COST: 15,000$ (Tanks /Piping/ Pumps/ Treatment, civil work not included)Note: Cost was affected in a positive way due to the system’s being part of thewhole project.

DATE: NOV. 2013 – MARCH 2014

The system was part of a complete water conservation and management plan forthe school that serves 410 students with 40 teachers and staff members. Theproject includes waste water treatment plant and rainwater harvesting system.Water saving and rainwater use are the two main goals of the school to cover forthe shortage in municipal water supply. The school, on the average, was alwaysshort of 50% of its need from municipal water. The rainwater harvesting covers theshortage and replaces the need to buy 3,000-4,000 liters / Week. 2 polyethylenetanks 22,000 liter each, were placed to store 44,000 liters of collected rainwater(22,000 x 2) that will be treated after collection to become good for domestic useand will be stored in a 22,000 liter PE tank. The collected water is used for toiletflushing, teachers’ toilet wash basins and for cleaning the school.

On site, there was no problem in placing the RWH tanks. It had the perfect locationarea as to the whole project, for the waste treatment plant and for the rainwaterharvesting system that was a dead unused space. This made the cost related toplacement and connection as minimal. A reinforced concrete platform wasconstructed to insure well placement of tanks after excavations and leveling.Overflows of rainwater tanks were directed towards the forest nearby.

The system showed its success due to the amount of rainwater that was collectedand used. The tanks are still full in the summer season, so the school will have nowater shortage when school year starts in September especially that municipalwater supply was cut in mid-summer season.

Sponsor:HSBC (MENAcompetition for 4 publicschools as part of anawareness campaign.)

Client:arcenciel

Designer: SustainableEnvironmental Solutions- SES

Case study.qxp_Layout 1 1/25/17 4:31 PM Page 124

125

CASE STUDY # 2A MULTI-DISCIPLINARY CENTER

PROJECT: ARCENCIEL TAANAYEL CENTER - Nursery / Workshop / Restaurant

LOCATION: TAANAYEL – ZAHLE (CAZA) – BEKAA (MOUHAFAZA)

ALTITUDE: 830 m

APPLICATION: TOILETS FLUSHING, FAUCETS AND CLEANING

SYSTEM: 2 ABOVEGROUND PE TANKS 22,000 X 2 = 44,000 L TO CONTAIN THERAINWATER, TREATMENT PLANT FOR DOMESTIC USE, PUSH BUTTONFAUCETS IN TOILETS

CATCHMENT AREA: CONCRETE ROOF, AREA OF 300 m2

COST: 25,000 $ (Tanks/Piping/Pumps/Treatment/included civil work of roof)

Note: Cost was affected negatively due to being one of the first projectsimplemented by the company, thus it was time consuming and had higherengineering cost.

DATE: 2013

In response to the drought and as part of an ongoing effort towards a moresustainable location, the center built a rainwater collection system for domesticuse and toilet flushing. With the growing shortage in municipal water supplyand the continuous need to pump from the center’s water well, the rainwatersystem was a need to the center that serves 300 persons. 2 polyethylene tanks22,000 liter each, were placed to store 44,000 liters of collected rainwater(22,000 x 2), that would be treated after collection to become good fordomestic use, after which water will be mixed with municipal water in thecenter’s already existing tanks.

In winter, the rainy season, water well pumps and treatment plant would beturned off so to retain water volume in the well and help replenishing the watertable to its normal natural levels. In summer season, when no more municipalwater supply and water well level is low or no good (smelly), then, watertreatment plant would be turned on. Nevertheless, the RWH system will be fullyoperational in the winter season to cover the shortage from the municipalwater. This will result in lengthening the lifespan of the underground water,instead of using the underwater during the whole year they will use it onlyduring summer season, thus resulting in better water quality with lowerpollution concentration.

The system showed its success due to the amount of rainwater that was collectedand used. The tanks are still half full in the summer season, end August.

Sponsor: Coca Cola Fund / UNDP

Client: arcenciel

Designer:SustainableEnvironmental Solutions– SES



CASE STUDY # 3A PRIVATE SCHOOL

PROJECT: AVE MARIA SCHOOL

LOCATION: ASIA – BATROUN (CAZA) - NORTH LEBANON (MOUHAFAZA)

ALTITUDE: 800 m

APPLICATION: TOILETS FLUSHING AND CLEANING

SYSTEM: 3 ABOVEGROUND PE TANKS 10,000 X 3 = 30,000 L TO CONTAIN THE RAINWATER

CATCHMENT AREA: TILED ROOF, AREA OF 400 m2

COST: 10,000 $ (Tanks/Piping/Pumps)

Note: Cost was affected negatively due to being the first project to beImplemented.

DATE: NOV 2013 – MARCH 2014

Encouraged to take some action as a response to draught, the school wantedsupplemental water to use for toilet flushing and cleaning. The school that serves200 students with 30 teachers and staff members, already had an undergroundexisting concrete tank of 70,000 liter supplied with municipal water. The30,000 liters of harvested rainwater will only be screened from debris and leavesbefore being collected and mixed with municipal water. At the end of the projectimplementation, the school had a total volume of water storage equal to100,000 liters.

Water is currently flowing over, so no water problem.

Sponsor:Coca Cola Fund / UNDP

Client:arcenciel

Designer:SustainableEnvironmental Solutions– SES


127

CASE STUDY # 4RESIDENTIAL BUILDING

Sponsor:Private

Client: Sarkis Family

Designer:R.Sarkis Consultant

PROJECT: SARKIS BUILDING

LOCATION: KENNABET BROUMANA – METN (CAZA) – MOUNT LEBANON (MUHAFAZA)

ALTITUDE: 450 m

APPLICATION: ALL DOMESTIC USE AND IRRIGATION

SYSTEM: REINFORCED CONCRETE TANK 40 m3

CATCHMENT AREA: BRICK TILED SLOPED ROOF, 2 SURFACES 100 m2 x 2 = 200 m2

COST: MINIMAL - None

DATE: 1994

The building’s design was a reflection of the owners’ belief and awareness ofenvironmental issues, water in particular. The rainwater harvesting system waspart of the design of the building from its early stages. The building was not linkedto municipal water due to multiple reasons one of which was the condition ofmunicipal conveyance system. A 40 m3 concrete tank was built on the basementlevel to store rainwater collected from 2 brick tiled sloped roofs as catchmentsurfaces of 200 m2 area. This collected water is used by 4 families of around20 people for all their domestic daily use and irrigation. No extra charge wasneeded due to the fact that it was the same charge accounted for the waterconveyance system to be used. No special water treatment was implemented;only the addition of chlorine on regular basis is done, as disinfection.

Up until this year, water crisis year, the collected rainwater was being used fromSeptember till June of every year without any problem; about 9 to 10 months.Owners have future vision of exploiting an unused area of 140 m2 flat roof withwater treatment to be accounted for as well. They also have a belief in theimportance of legislation and incentives in relation to the system’s publicspreading.



CASE STUDY # 5SOS VILLAGE

PROJECT: KFARHAY SOS VILLAGE

LOCATION: KFARHAY – BATROUN (CAZA) - NORTH LEBANON (MOUHAFAZA)

ALTITUDE: 400 m

APPLICATION: IRRIGATION, TOILETS FLUSHING AND CLEANING

SYSTEM: REHABILITATION (PIPING, PUMPS, SHOWER HEADS AND FAUCETS)

CATCHMENT AREA: - - - - -

COST: 3,500 $ (Piping/Pumps)

DATE: 2014

The village design that was done by a German architect in mid-90’s, which alreadyincorporates rainwater harvesting tanks under all 10 houses from their roofs ascatchment areas. Pumps pull water from house tanks to the main concrete towerwhich in itself is divided into 4 compartments for different water usage.

To keep the system working efficiently, rehabilitation was done to conveyancesystem and all leaking pipes and pumps were changed. This was part of a biggerproject including a waste treatment plant and drop irrigation system. The collectedrainwater will be added to the treated waste water and used for irrigation, toiletflushing and cleaning.

All shower heads, toilet faucets and kitchen faucets were changed as part of acomplete water conservation and management plan.

Sponsor:HSBC

Client:SOS Villages

Designer:SustainableEnvironmental Solutions- SES


finalprint.indd 1 2/15/16 2:01 PM


UNDP is the UN's global development network, advocating for change and connecting countriesto knowledge, experience and resources to help people build a better life. We are on theground in nearly 170 countries, working with them on their own solutions to global andnational development challenges. As they develop local capacity, they draw on the peopleof UNDP and our wide range of partners.

For More Information:

United Nations Development ProgrammeArab African International Bank BldgBanks StreetNejmeh, Beirut 2011 5211LebanonE-mail: [email protected]: lb.undp.orgFacebook: www.facebook.com/UNDPLebanonTwitter: twitter.com/undp_lebanonInstagram: instagram.com/undp_lebanon

Ministry of Energy and WaterGround Floor, Corniche du FleuveBeirut, Lebanon.Website: www.energyandwater.gov.lbTelephone: 01-565100

NATION

AL GUIDELINE FOR RAIN

WATER HARVESTIN

G SYSTEMS



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