Rainwater Harvesting 101 - Grow New York City
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Transcript of Rainwater Harvesting 101 - Grow New York City
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Rainwater Harvestin 101
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RAINWATER HARVESTING 101
COUNCIL ON THE ENVIRONMENT OF NEW YORK CITY
Robert J. Kafin, Esq., Chairman
Marcel Van Ooyen, Executive Director
Prepared by:Julia Leung, DEC Summer InternforCouncil on the Environment of New York City51 Chambers Street, Room 228New York, NY 10007(212) 788-7900
August 2008
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PREFACE
The Council on the Environment of NYC (CENYC) is a hands-on non-profit that has been improving NewYork City's environment for over thirty years. CENYCs dedicated staff green our neighborhoods, create theenvironmental leaders of the future, promote waste prevention and recycling, and run the largest farmersmarket program in the country. CENYC achieves its mission through the following projects and programs:The Open Space Greening Program, Greenmarket, The New Farmer Development Project, EnvironmentalEducation Training Student Organizers, Learn It, Grow It, Eat It and Office of Recycling Outreach andEducation.
The Open Space Greening Program (OSG) empowers people in neighborhoods throughout the city tocreate, manage and sustain community gardens and park/playgrounds. OSG provides best practicesworkshops, services, tools, donated plant material, and open space planning/mapping information andother services. Grow Truck provides tools, donated supplies, plants and horticultural advice and assistanceto gardening groups all over New York City. The Plant-A-Lot Project gives substantial material and
technical assistance to several new gardens each year and helps the 45 existing gardens created in prioryears.
Since 2002, OSG staff has taken the lead in building and maintaining rainwater harvesting systems incommunity gardens across the five boroughs, leading educational workshops, assisting communitygardeners in identifying alternate water resources and building low cost systems. CENYC is an activemember of the Water Resources Group, a network of NYC greening and environmental organizationspromoting sustainable water conservation practices in NYC. The New York State Department ofEnvironmental Conservation (DEC) recognized CENYCs efforts with The Environmental Excellence Awardin 2006. This manual was created to disseminate to a wide audience the design parameters and buildingtechniques used by CENYC staff.
Summer intern was able to prepare this document thanks to a grant from The New York State Departmentof Environmental Conservation in 2008 for Pollution Prevention. Ms. Leung provided many of the photos,charts, and drawings used. OSG staff, Lars Chellberg, and Lenny Librizzi provided invaluable guidance,advice, and editing of the manual. CENYC Executive Director Marcel Van Ooyen and Assistant ExecutiveDirector Julie Walsh edited the text. Additional information and assistance was provided by NYCcommunity gardeners and members of the Water Resources Group.
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TableofContentsIntroductionofRainWaterHarvesting 2
Historyof
Rain
Water
Harvesting
5
BenefitsofRainWaterHarvestinginUrbanAreas 6
CurrentEfforts 7
Materials 10
Wheretoobtainsupplies 11
CostEstimates 12
PVCApplications 14
Sizingofthetankandroofwasher 18
Construction 21
Tank
23
Leaders 26
RoofWasher 30
Overflow 33
Anchoring 36
DripIrrigation 39
FiltrationSystems 41
Treatment 42
Aesthetics 43
RoofingMaterial
45
SeasonalMaintenance 46
LivingwiththeRWHsystem 47
ExistingRWHSystems 48
10WaystoConserveWater 49
Bibliography 50
FeedbackForm 51
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1
Introduction"Itisn'teasytocomeupwith'onesizefitsall'instructionsforbuildingrainwaterharvesting
systemsbecause
of
variations
in
styles
of
roofs,
downspouts,
storage
tanks,
and
garden
layouts.
Youhavetouseacombinationofresearch,commonsense,ingenuity,anddumblucktodesign
andbuildyoursystem."
LennyLibrizzi,AssistantDirectorofOpenSpaceGreeningattheCENYC
Rainwaterharvesting(RWH)isthemeansofcollectingandstoringrainwaterinlarge,durable
containers,usually,collectingfromrooftopgutters.RWHsystemscomeinavarietyofshapes
andsizes(seepicturesbelow).
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Rainwaterharvestingsystemsarefairlyeasytoconstruct.TanksinNYCcommunitygardens
rangeinsizefrom300to1000gallonsbutcanbeassmallas55gallonsandasbigas10,000
gallons.Rainwatercollectedfromthedownspoutofanadjacentbuildingorshedinthegarden
isredirectedtothewaterstorageareainthegarden.TheRWHsystemincludes3parts(see
drawing):thetank(1),thefirstflush(2)andtheoverflowpipe(3).
Duringarainfalleventwaterfromthegutter flows intothedownspout. Insteadofthewater
goingintothesewersystem,therainwaterharvestingsystemdivertsthewaterintopipes.This
diverterconsistsofa3wayteewithaplungerinplaceduringthesummer.Thisplungerkeeps
thewaterfromenteringthedownspoutandforces ittoflow intotheharvestingsystem. It is
takenoutinthewinterwhenrainwaterisnolongercollected(4).
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Hereisacloserviewofhowtheplungerworks.
Thepipesleadtoaroofwashersystemwhichisacontainmentareaforthefirstfewgallonsof
water.Sincetheinitialflushesofwatercontainrooftopdebrisandleaves,theroofwasheracts
asafilteringsystembyseparatingthedirtywaterfromthecleanerwater.Oncetheroofwasher
isfull,thecleanerwaterenterstheraintank.Assoonasthetankisfull,excesswaterflowsinto
the overflow pipewhich leads to an adjacent rain garden (5), is directed back towhere itoriginallyflowedorpipedunderground.Araingardenisaplotcontaininghardyplantsthatcan
survivewithbothsaturatedanddrysoil.
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Historyofrainwaterharvesting
Rainwaterharvestingisanancientpractice.Manydifferentcultureshaveusedthistechnology
foragriculturalpurposes.ThePhilippineshavebeenusingrainwaterforriceterracesfor
thousandsof
years
now.
Indian
history
indicates
that
rain
water
systems
have
been
in
use
since
3000BC. Usagecanalsobetracedback2000yearsagoinThailandandotherpartsof
SoutheastAsia,wheresimplegutterswereusedtofilljarsandpots.Theearthdamsofancient
Egyptwereusedtocontrolrunoff.Ancientrainwatercisternscanstillbeseenontheislandsof
CapriandMalta.
Inadditiontorainwaterharvesting,theRomansalsousedtheirsystemsasairconditioners.
Whenthewaterevaporated,itcreatedacoolingeffectinthemicroclimate.Astheir
populationsstartedtoincrease,theRomansdevelopedundergroundcisterns.Thisway,less
waterwouldbelostduetoevaporation.Theyconnectedthesecisternstoabovegroundpools
asameansofwaterfiltration.Whenthesepoolsoverflowed,thecleanerwaterwouldenter
thecisterns.
This
design
was
an
inspiration
for
modern
day
rain
barrels.
The
Romans
shallow
poolmirrorsthemoderndayroofwasherorfirstflushsystem.
TheworldslargestcisternistheYerebatanSarayi,builtbyCaesarJustinianin527AD.Itis
locatedinmoderndayTurkeyandisapopulartouristattraction.Itis140metersby70meters
bigandcanstoreupto80,000metersofwater.Thishugestructureiscompletelyunderground
andinvolvesaseriesofintersectingvaults.BinbirdikisanothercisterninIstanbul,createdby
CaesarConstantinein389ADthatcanstore80,000meters.Howeverconstructionofthese
cisternsstoppedduetothedifficultyofbuildingundergroundandtheoutbreakofhumanfecal
contaminationinlargecities.1
Inthe
1970s,
anew
technology
of
rain
water
harvesting
was
developed
where
storm
water
wasstoredinwellstoragetanksintheformofdifferentsizedponds.Athinlayerofredclay
wasusedtolinethebottomofthepondtopreventseepageandtreeswereplantedaroundthe
pondtopreventexcessiveevaporation.Over40,000ofthesesystemswerebuiltintheLoess
PlateausofChina.2
Althoughrainwaterharvestingwasasignificantandsuccessfuldesigninthepast,itspopularity
hasdeclinedoverthecenturies.Urbanizationdemandedamorecentralizedwatersupply
system.Watershedsandpipelinescameintouseandrunningwaterbecameoneoftheworlds
greatestinventions.However,duetomoderndaywaterpollutionanddrought,rainwater
harvestingtechniqueshavecomebackintopracticeagain.
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Benefitsofrainwaterharvestinginurbanareas
Bykeepingstormwateroutofthesewagesystem,gardenershelpkeeptheirlocalwaterbodies
clean.BecausemostofNYCispavedover,rainwatercantbeabsorbedbytheground.Instead,
itruns
across
the
pavement,
picking
up
oil,
street
debris,
animal
feces
and
other
waste
as
it
moves. Thisrunoffthenentersthesewersystem.
Unfortunately,notallrunoffmakesittoatreatmentplantbeforeenteringthecitysriversand
harbor. ThisisbecausemostofNYCisonacombinedsewersystem,wherebythesamepipes
areusedtotransportbothstormwaterrunoffandhouseholdwastetosewagetreatment
plants.Ifthesetreatmentplantsoverflow,thecontaminatedwaterthenentersthewater
bodiessurroundingNYC.
Duringdryweatherthesewagetreatmentsystemgenerallyworkswell,butthesetreatment
plantscanonlyhandleabouttwicetheirdryweathervolume.Thismeansthatheavyrainsoften
resultin
combined
sewer
overflows
(CSOs),
which
release
untreated
wastewater,
storm
water
andstreetdebrisintolocalwaterways.Untreatedsewagecancarrydiseasecausingpathogens
andnutrientrichorganicmaterial,whichcanchoketheHarborsecosystem.
Notonlycanrainwaterharvestingpreventwaterpollution,italsoconserveswater.Typical
systemscanstoreupto1000gallonsofwater.Harvestingduringrainydaysinspringand
summerprovidesasourceofwaterforthedryspellsbetweenrainevents.Insteadofrunning
thehosetowateryourgarden,youcanusetherainwaterstoredinyourtank.Thiswillrelieve
thestrainonourreservoirsandalsosaveyoumoneyonyourwaterbill.Fortypercentof
householdwaterconsumptionisusedondomesticirrigation!3
Rainwaterharvesting
has
proven
to
be
successful.
The
35
rain
water
harvesting
systems
workinginNYCscommunitygardenscollect422,900gallonsofwatereveryyear.Thatsenough
for264,313toiletflushes!
Ofcoursesmallscaleconstructionofrainwatersystemsisnotenoughtosignificantlyimpact
ourenvironment.However,ifrainbarrelswereusedmoreextensivelyandraingardensbecame
alargerpartofcitylandscapeplanning,waterconservationwouldhaveagreater
environmentalimpact.Wewouldexperiencecleanerwaterbodies,lessfloodingandlower
watercosts.
Rainwaterharvestinghasgreatpotentialtoreducerainwaterflowintostormdrainsby
collectingrainwater
in
gardens
and
can
reduce
the
dependence
on
the
NYC
watershed.
Every
dropofwatercountsandconservationisthemostsustainable,costeffectivesourceofwater
supplyforourregion.
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Currentefforts
CommunitygardenersacrossNorthAmericaandaroundtheworldhaverevivedthepracticeof
usingrainbarrelsintheirgardensoutofnecessity.
InSeattle,budgetconstraintsandrisingwaterpricesspawnedtheconstructionofrainwater
harvestingsystems.SomeofSeattlesrainwaterharvestingsystemsareworksofart.Heregate
pillarssupporttheflowofrainwaterfromthebuildingontherightintothecisternontheleft.
SeattlePublicUtilitieshaverecommendedchangestothelanduseandbuildingcodesthat
encouragewaterconservation.SPUhasalsosponsoredsomewildlysuccessfulsalesofrain
barrelstoSeattleresidents.
The10,000RainGardensPrograminKansas
Cityisanexampleofregionaleffortsto
educateandintroducewaterconservationto
theKansasCitycommunity. Raingardensare
areasofvegetationonporousgroundthatcan
filter
and
drain
excess
storm
water.
Kansas
Cityofficialsencouragetheirresidentstoplant
thesegardensontheirownproperty.
Thespecial
curves
on
this
gate
represent
the
monthly
rainfallinSeattleandtheamountofwatercollected
yearround.
Theoverflow
pipe
of
this
Seattle
cistern
creates
amini
waterfall.
AcatenjoyingtheraingardeninKansasCity.
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TheCityofVancouverdesignsandmanufacturesrainbarrelsforresidentstousefor
irrigation(seepictureonright).Vancouversubsidizesthecostoftherainbarrelsby
50%.Over2000barrelshavealreadybeensold.
Portland,Oregon,grantedapermitforahouseholdtoharvestrainwaterfor
useindoorsduringallbutthedrysummermonths(seesketchandpicture
below).ThewaterundergoesenoughfilteringtomeetEPAsstandardsfor
drinkingwater.In1998thissystemcostlessthan$1,500toinstall.
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Maplewood,Minnesotahasforgedacoalition
betweenitswaterandsanitationdepartments
andresidentiallandownerstoplantlargescale
curbsideraingardensthatreducestormwater
sewage(seepictureonleft).
TheMinnesotaArboretumusesitsparkinglotsto
demonstratebestlandscapepracticessuchas
plantingraingardensandusingpermeablepavers
toreducecontaminationcausedbystormwater
runoff(seepictureonright).
TheCityofTorontoDownspoutDisconnection
Program
offers
a
free
service
to
homeowners
to
disconnectdownspoutsfromthesewersystemand
installrainbarrelswhichareavailableatadiscount.
Chicagoalsoencouragesitscitizenstodisconnect
downspouts.Inaddition,ChicagosWaterAgenda2003includedarooftopgardeninitiative,a
pilotprogramforpermeablealleys,andraingardensplantedintheCitysrightsofway.
Austinoffersrebatesofupto$30fornewlyinstalledrainbarrelsandofupto$500for
installationofrainwaterharvestingsystems,followingdesignapprovalbytheCity.
In2001,
the
first
Drought
Emergency
to
be
announced
since
1989
was
declared
in
New
York
City.Thereservoirlevelswere40%belownormalwhichresultedinmandatorywateruse
restrictions.TheWaterResourcesGroup(WRG)wasfoundedasaresponsetothissingle
droughtyear.SincethenWRGandCENYChavebuilt35rainwaterharvestingsystemsinNew
YorkCity,collectingover422,900gallonsofstormwaterperyear.
NewYorkCitycurrentlylagsbehindothercitieslikeBostonandChicago,whichcapture90%of
theircombinedsewageoverflow;NewYorkCityonlycapturesabout70%,accordingtothe
city4
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Materials
Everyrainwaterharvestingsystemisdifferentbut
theydohavesimilarities.Hereisacomprehensivelist
oftools
and
supplies.
Your
system
will
use
many
of
thesebutmaynotrequireallofthem.
Tools:
Drill Holesawattachmentorjigsaw Screwdrivers Hammer Level PVCsaw(seetopsawinpicture)andmetalhacksaw(bottomsaw) Tinsnipsorsheetmetalshears Crimpingtool(seepictureonright)andcablecuttingtools
Gutters:
Gutterlengths Leadersandbends Prefabricatedgutterhangers Plumbingstrap(forsecuringpipestowall) Flexible,accordionstyleexpandableplasticpipe Tubeofguttersealantandcaulkguntoapplyit PVCcleanerandcement Teflontape(forcreatingawatertightsealonthreadedbushings)
Barrelstoragesystem:
TanksandPVCpartsorothermaterialstoconstructthemanifold.Herewehavea
capped4waytee(seeleftmostpicture)
anda90and45elbowrespectively(see
rightmostpicture)
Windowscreenorscreenedventsformosquitoproofvent
Bulk
head
fittings
(An
elongated
compression
fitting,
which
will
allow
pipe,
to
run
throughabulkhead)
Platformmaterialsuchastreatedlumber,plasticlumberorconcreteblocks Eyebolts(forsecuringtank) Spigot Metalflangesofcorrespondingsizetospigotandhardware Ropeorcablingsuppliestosecurethetank
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Wheretoobtainsupplies
Polyethylenetanksarebestpurchasedlocallybecauseofhighshippingcosts.Searchonlineforlocalsuppliers.Youcanpersonallyshipsmallertanksandsaveonextraexpenses.Hereare
somewebsites
that
sell
tanks:
http://www.liquidlogictanks.com/index.html http://www.tankdepot.com/ http://www.rainbarrelsource.com/ http://www.rainbarrelsandmore.com/ http://www.aquabarrel.com/
Dripirrigationsuppliersinclude: http://www.dripdepot.com/ http://www.dripirrigation.com/ http://www.rainbird.com/drip/index.htm http://www.dripworksusa.com/ http://www.netafim.com/ http://www.chapindrip.com/ http://www.farmtek.com
Downspoutfiltersandavarietyofotherspecializedpartsforsystemscanbepurchasedfrom: http://www.starkenvironmental.com/a1filtration.html http://www.braewater.com/ http://www.rainharvesting.com.au/default.asp http://downspoutfilter.com/index.php http://rainharvest.com/shop/default.asp
ToolsandPVCgutterpiecescanbepurchasedatyourlocalhardwarestores.LowesorHomeDepotalsosellstheseitems.Forlocationsnearyou,visittheirwebsitesat
http://www.lowes.com/orhttp://www.homedepot.com.
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CostEstimates
Notethatthepriceslistedindicatethevaluesin2008.Adjustfora15%20%annualincrease.
Polyethylenetanks:
Generally,
tanks
cost
$1
per
gallon
but
it
can
sometimes
be
too
big
to
transportonyourown.Shippingcostsareaboutanadditional$1pergallon.
LeadersandGutters:Thenumberofleadersandguttersneededpersitewillvarydependingontheroofconfiguration.A10footlonggutteris$15.00,a10footlong2x3leaderis$9.00,and
a10footlong3x4leaderis$16.00.Connectingparts,cornersandbendsareanywherefrom
$2.00to$10.00.
Platforms:Platformsforcontainerscanbemadeoutofcinderblocks,plywoodoranyother
sturdymaterial.Whilethetankislightwhenitisempty,rememberthatafulltankofwatercan
weighthousandsofpounds.Asmall55gallontankweighsover400poundswhenfull!Besure
thatyourplatformisstrongenoughtowithstandlargeweights.Cementblockscanbe
scavengedfromconstructionsites.Shouldyouhavetopurchasethem,8x16cementblocks
are$1.50each.Thelumberpricesare$16.00forapressuretreated8footlong2x10piece
or$13.00forapineorfir8footlong2x10piece. An8footlong4x4piececosts$12.00.
4x4lumberlaidlengthwiseinalternatingdirectionsplacedonagravelbasemakesasturdy
platform(seepictureonpage25).Usingpouredconcretepilingsandabuiltwoodendeckfora
platformmaycostabout$500.
MiscellaneousHardwareandspecializedparts:Thiscategoryincludesaccordionconnectorpieces,screens,sealants,sheetmetal,screws,nuts,bolts,gravel,filteringpartsandsupplies,
roofwashers,weedfabricandotherspecializedparts.Thesepartswillvarybysiteandtypeof
barrel.
PlumbingSupplies:Theamountofplumbingyouneedvariesdependingonthesystemyouaremaking. Thiscategoryincludesoverflowpieces,PVCpipes,connectorpieces,rubberfittings,
spigots,bulkheadfittingsandthepipingneededtodrawthewaterawayfromthesystem.
Upgradeswillincludesoakerhosesorothertypeofoverflowdisperserandroofwashers.A
sophisticateddripirrigationsystemcouldadd$5001000tothecost.
ToolKit:Somespecialtytoolsareneededsuchasdrillbits,screwbits,hacksawblades,tinsnips,holesaws,caulkgun,caulkingorsilicon,jigsaw,pliersandtapemeasures.
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Costanalysisfora300gallonrainwatersystemin2008
Tank $300
ShippingofTank $300
LeadersandGutters $100
Platform
$300
Hardware $100
Plumbing $100
ToolKit $50
TotalCost $1250
Costanalysisfora1000gallonrainwatersystemin2008Tank $1000
ShippingofTank $1000
Leadersand
Gutters
$200
Platform $600
Hardware $200
Plumbing $200
ToolKit $50
TotalCost $3250
Ifthereisnotalreadyanexistingrooforshednearby,ashade
structurecan
be
constructed.
One
possible
design
is
the
winged
structureseenhere:
Costanalysisfora300gallonrainwatersystemwithwingedstructurein2008Tank $300
ShippingofTank $300
LeadersandGutters $100
Platform
$300Hardware $100
Plumbing $100
ToolKit $50
MaterialsforShadeStructure $2500
TotalCost $3750
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PVCApplicationsUptonowPVCorpolyvinylchloridehasbeenthekeypipingmaterialintherainwater
harvestingsystemsinNYCcommunitygardens.Thishardplasticisinexpensive,durable,easyto
useand
readily
available.
Tees,
elbows,
bushings
and
couplings
are
all
made
out
of
PVC.
AlthoughPVCisfairlystable,thereareenvironmentalhazardsinmanufacturingandburning
PVC.Wearecurrentlylookingforothersourcesthataremoreenvironmentallybenignbutalso
havingthesameflexibilitywithpartsasPVCdoes.Althoughmetalcanbeanalternative,itcan
becostly.IfthereisamaterialthatyouthinkcanbeareplacementforPVC,pleaseaddyour
informationorcommenttothiswiki:
http://www.waterresourcesgroup.org/wiki/index.php?title=Main_Page.
InordertojoinPVCpipestogether,usePVCspecificcleanerprimerandcement.PVCcleaner
primerremovesdirtandmeltsthesurfaceforultimateadhesion.Afterthepipeisclean,you
canusecementtojointhetwopiecestogether.Onlyapplycleanerandcementtotheoutside
partof
the
male
piece
(see
picture
on
left)
and
the
inside
part
of
the
female
piece
(see
picture
onright).Itisimportanttoholdthetwopiecestogetherfor20secondsafterapplyingthe
cementbecausetheymaymoveapart.After20seconds,thetwopiecesarepermanently
joined(seebottommostpicture).Wipeoffexcessglue.
Usebushingsandreducerfittingswhenitisnecessarytochangethesizeofyourpipes.These
comeinawidevarietyofglue(slip)andthreadeddesigns.
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This2x1slipbushingconnectsa2(diameter)pieceofpipe
witha1pipe.Slipbushingscanbeadheredusingthecleaner
andcementmethodmentionedabove.
This2x1slipandthreadbushingconnectsa2slippipewitha1threadedpipe.Thread
bushingscanbeadheredtightlyusingTeflontape.Rollthetapestartingattheendofthemale
threadbushingtowardsthemiddle.Twoorthreewrapsaresufficient.
PVCpartsareveryversatilesincenotworainwaterharvestingsystemsarealike.Many
differentcombinationsofPVCpartscanbeusedforthesamefunction.Hereare5different
waystoconnecta2pipewithapipe.
Itisveryimportanttoalignadjacentpipes.Thetwoteesinthefirstpicture(seepicturebelow)
mustalignexactlyinordertoconnecttothesamewall.Carelessglueingwillleadtoproblems.
Useahard,levelsurfacesuchasaconcretefloortohelpyoualignpipes.
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Thepipesinthesecondpicture(see
pictureonleft)mustbeexactly
perpendiculartoeachother.Theteeon
theleftwillconnecttothebarrel.Thetee
ontherightwillconnecttoexistingpipes.
Useamarkertoindicatethepointswhere
theonepipemustmeettheother.
Thepicturesabovealsopointouttheuseofpiping.Noticehowthetwoteesarejoinedineach
picture.Inthesecondpicture,thetwoteesarejoinedbyusingasmallpieceofpipeinbetween
them,calledasleeve.Theinteriorcouplingistooshorttobeseeninthispicture.Inasituation
whereyouwanttheteestobefurtherapart,suchasinthefirstpicture,justextendthesizeof
thepipetothedesiredlength.
Althougheveryrainwatersystemmustbecarefullyplannedbeforeactualconstructionbegins,
itisveryeasytomiscalculateormeasureincorrectly.Oftentimes,errorsarenotrealizedat
first.To
fix
ameasurement
or
connection
problem
where
the
2pipes
that
were
intended
to
connectdonotmatchup,usetwo45degreeelbows.Acombinationoftwo45elbowswill
producealmostanytwistorangledesired.
Two45
elbowscan
makea90
degree
twistor
a
180
degree
twist.
Twopipesthat
didnot
connectbefore
cannowbe
connected
withthe
help
oftwo45
elbows.
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ItisalsopossibletoshortenthePVCpipebycuttingandreconnectingitwitharubbercoupling.
Noticethatthepipebelowistoolongtoconnectwiththesmallerpipesattachedtothewall
(seetoppicture).Itwasshortenedandreconnectedusingarubbercoupling(seebottom
picture).
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Sizingofthetankandroofwasher
Avarietyofrainwatersystemscanbeconstructedforthesamedownspoutandroof.Hereare
twodifferentsystemsthathavebeeninstalledovertheyearsatthe1100BlockBergenGarden
inBrooklyn.
It
is
generally
better
to
have
asingle
barrel
rather
than
multiple
barrels
because
of
possibleleakagefromthenumerousconnections.The9barrelsintheoriginalsystemhad17
connections.Therewere17locationswhereleakagecouldoccurasopposedto1locationinthe
currentsystem.
Thecapacityofthesystemshouldbedeterminedbytwofactors:thesizeoftheroof,which
determineshowmuchwatercanbecollectedandthesizeofthegarden,whichmeasureshow
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muchwaterisneeded.A300gallonverticalcylindricalstoragetankisapproximately42inches
indiameterand51inchestall.A1000gallonpolyethylenetankisapproximately92inchesin
diameterby60inchestallor61inchesindiameterby100inchestall.
Theamountofwateryoucanharvestvariesdependingonthesizeofyourroof.Youwillbe
surprisedhow
much
water
you
will
be
able
to
collect
from
even
the
smallest
roof.
The
rule
of
thumbis600gallonsofwaterperinchofrainperthousandsquarefeetofcatchmentarea.
Notalltherainthatfallscanactuallybecollected. Efficiencyisusuallypresumedtobe75%
dependingonsystemdesignandcapacity. Hereisthebasicformulaforcalculatingthe
potentialamountthatcanbecollected:
(Catchment area) x (inches of rain) x (600 gallons) x (.75)
________________________________________________
1000 square feet
Rememberthataroofcanhaveseveraldownspouts.Yourcatchmentareaonlyconsistsofthe
regionwhere
the
downspout
that
is
connected
to
the
rain
barrel
collects
from.
Pay
attention
to
thegutterandslopeoftherooftodeterminewhichpartisyourcatchmentarea.Inorderto
calculatethecatchmentarea,usemeasuringtapetodeterminethewidthandlengthofyour
roofinsquarefeet.Multiplythelengthandwidthofyourcatchmentareafortheareaofyour
roof.
Thesampleroofshownbelow(seepicturebelow5)hasacatchmentareathatis40feetwide
and30feetlong.Hence,ithasa1200squarefeetroof(40feetwidex30feetlong).Assume
thatitrains2inches.Wecannowplugthisinformationintoourgeneralformula(seeequation
above).
CatchmentArea=1200squarefeet
AmountofRain=2inches
Gallonsofwatercollectedperinchofrainper1000squarefeet=600gallons
Percent
Efficiency
=
75%
or
.75
(1200 square feet) x (2 inches of rain) x (600 gallons) x (.75)
__________________________________________________ = 1080 gallons
1000 square feet
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Thereforea1200squarefootroofwillcollect1080gallonsofwateronadaywith2inchesof
rainfall.Usingthisformulaandyourregionsaveragerainfallnumberscombinedwithan
estimatedwaterneed,youshouldbeabletocalculatetheapproximatesizeofyourtankor
barrelsystem.
Roofwashersizesalsodifferaccordingtothesizeoftheroof.Theruleofthumbisonetotwo
gallonsofroofwashercapacityforevery100squarefeetofcatchmentarea.A1footlengthof
6inchdiameterPVCpipeholds1.5gallons.A1footlengthof4inchdiameterPVCpipeholds
.66gallons.
Wewillusethesame1200squarefootroofshownaboveasanexample.Sincetheruleof
thumbsuggestsonegallonofroofwashercapacityforevery100squarefeetofcatchment
area,thesampleroofwillneed12gallonsofroofwashercapacity.
Ifyouareusing6inchdiameterpipe,usethefollowingformula:
Number of gallons of roof washer capacity
__________________________________
1.5 gallons/ feet
Thesizeofourroofwasheronoursampleroofcanbecalculatedby:
12 gallons of roof washer capacity
______________________________ = 8 feet of 6 pipe
1.5 gallons / feetIfyouareusing4inchdiameterpipe,usethefollowingformula:
Number of gallons of roof washer capacity 12 gallons
____________________________________ = _________________ = 18 feet of 4 pipe
.66 gallons / feet .66 gallons/ feet
Thereforea1200squarefootroofwillneed8feetof6diameterpipeor18feetof4diameter
pipe.Rememberitispossibletoseparatelonglengthsofroofwashersintoseveral,continuous
pipesinsteadofjustonelongpipe.
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ConstructionThefirststepoftheconstructionprojectistomakeaplandrawing.Theplandrawingconsiders
thelocation
of
the
downspout
and
the
amount
of
space
available.
Each
system
must
include
thetank,thefirstflushandtheoverflow.Herearesomeissuesthatshouldbeconsideredin
yourplanning:
Themoststableplacetopositionyourbarrelisagainstastablewallonlevelgroundasclose
tothedownspoutaspossible.
Gravitymoveswaterdownhill.Besurethereisavailablespaceforadownwardpitchinall
pipes.
Thebarrelonitsplatformisthehighestpointofthegardenbutthelowestpointofthe
system.
Theoverflowpipeshouldbedirectedtowardaraingardennottowardpathwaysor
structures.
Theoverflowpipeshouldflowfromthebarrelshighestpoint.
Thespigotshouldbeatthebarrelslowestpoint.
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Tanks
Tankscanbemadefromallsortsofmaterialssuchascement(seepictureonleft6),metal,
ceramicandwood(seepictureonright7).Intropicalcountries,aterracottatankcanbeused.
Nowintering
tee
is
necessary
for
these
tanks
because
there
is
no
danger
of
freezing.
Fordesignpurposes,bladderscanalsobeusedtostore
waterinsteadoftanks.Bladdersarelarge,flexiblebags
functioninginawaysimilartothewaterballoon(see
pictureonleft8).Thisway,engineerscancreatestorage
tanksinavarietyofshapesinsteadofthetraditional
cylinder.
Thetanksystemincludesthespigot,theinflowpipe,theoverflowpipe,thelidandtheplatform
itrestson.
Spigot:Avarietyofbushingscanbeusedtoconnectthespigot.Itispreferabletouseasingle
reducerbushingbutthatisoftennotpossible.Forexample,thetanksspigotholeis2inchesin
diameter.Thespigotpicturedhereisaballvalvehosebib.Inordertoreducethe2opening
tothespigot,thefollowing3bushingswereused:
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Lid:Thelidshouldremainclosedatalltimes.Stillwaterisahavenformosquitolarvae.Inspect
thelidandanyventsannuallyandcleanasnecessary
InflowandOverflowpipes:Sometankscomewithbulkheadfittingsinstalledfortheinflowandoverflowpipes.Forthosethatdont,aholesawisusedtodrillalargeholeinthebarrel.Two
bushingpieces,liketheonespicturedbelow,areusedtofashionabulkheadfitting.
Useamarkertotracetheholeyouwillcutforthethreadedbushings.Maketheholetightto
thethreads.Oncetheholeisprepared,threadthefirstpieceinfromtheoutside.
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Threadthesecondpiecefromtheinsideofthetankusingaflexiblewrench.Useguttersealant
tocreateawatertightseal.
Platform:Thepurposeoftheplatformistoraisethetankenoughtogetyourwateringcanunderthespigotandtocreatepressureflowforahose.Spreadathickgravelbaseoveranarea
slightlylargerthantheplatform.Thiswillpromotegooddrainageandallowforfinalleveling
oncethe
platform
is
built.
Astablearrangementofcementcinderblocks,likethisone,makesagreatplatformforsmall
55gallontanksbutisnotidealforlargertanks.Sincetheblockseasilyshift,rotresistant4X4
or6X6lumberlaidoutinalternatingrowsisthebestoptionforaplatform.Steelplatforms
arealsoapossibilitybutaremorecostly.Besuretolevelandcompactthegroundwellwhere
thetankwillsit.
WarningSigns:Donotdrinkthewatercollected.Onlyuseittoirrigateyourgarden.InstalledPVCisinertanditisusedasawatersupplypipe
forhouse
trailers
and
other
homes.
The
possible
contamination
is
almostexclusivelyfromharmfulbacteria.Forwatertomeetdrinking
waterstandardsitmustbetreated,usuallywithchlorine,oftenfiltered
andsometimestreatedwithultravioletlight.Awarningstickerorsign
shouldbeplacedonyourrainbarreltoavoidthepossibilityofanyone
mistakenlydrinkingthewater.
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Leaders
Theleadersoftherainwaterharvestingsystemrefertotheseriesofpipesthatleadtothe
tank.Thisincludesthepipethatconnectsthedownspout,thewinteringtee,theroofwasher
systemand
the
pipe
that
connects
the
barrel.
Gravity
keeps
the
water
flowing.
Remember
to
putadownwardpitchonallpipes.Aquarterinchdownforeverylinearfootwillcreateanadequatepitch.Usealevel(seepicturebelow).Itmaybeusefulforsomeonetostandbacktovisuallycheckthe
pitchandhelpyouadjustthepipesasyouarepitchingthem.
Keepthepitchofyourpipeseven
anddownhill. Thepictureontopis
correct.Thepictureonthebottom
hasan
upward
pitch
and
will
create
problems.
Keeppipespitcheddownward.
DONOTpitchpipesupward.
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Connectingthedownspout:Ourintentwithrainwaterharvestingistodivertstormwater,storeitforfutureuseandkeepitoutofthesewers.Thereareseveraloptionstodiverttherain
water:inserta3wayteeintothedownspout(seepictureonleft)orconnecttheexisting
downspoutdirectlytotherainbarrel(seepictureonright).Youcandesignyourowncustom
diverteraswell.
Anotherpossibilityistoreplacethedownspoutentirelywithpipesleadingtoyourrainwater
harvesingsystem(seepicturebelowandonthenextpage).
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Connectingtothedownspoutisoneofthelaststepsinconstructionofyoursystem.Youdonot
wanttodisconnectyourdownspoutandstartcollectingrainwaterwithanunfinishedsystem.
Winteringtee:Thepurposeofthewinteringteeistoallowthewatertobedirectedbackintothe
sewers
during
freezing
temperatures.
Rain
water
should
not
be
collected
at
that
time
becauseitmayfreezeandcausebreaksinthesystem.Asimplewinteringteeutilizesa
removableplungerhead.Theplungerheadblockswaterflowintothesewerandforcesitto
enterthesystem.Itisremovedduringthewinterandrainwaterwilljustflowstraightdown
intothesewer(seepictureonleftanddiagramonpage4).Complicatedwinteringteesinclude
afilteringsystem.Itoperateswiththesameprinciplebutinsteadofaremovableplungerhead,
thereisaremovablefilterwhichcatchesdebris(seepictureonright).
Roofwashersystem:RefertoRoofwashersonpage30.Connectingthebarrel:RefertoTanksonpage23.
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Herearesomeideastohelpyouwiththedesignofyourleader.
INFLOW
1:90elbow
2:4"pipe
3:90elbow
4:45elbow
5:4"pipe
6:45elbow
OVERFLOW
7:2"bushing
8:90elbow
9:2"pipe
INFLOW
1:downspout
2:4"rubbercoupling
3:cap
4:4way
tee
5:rubbercoupling
6:90elbow
7:4"sleeve
8:4"rubbercoupling
9:3waytee
OVERFLOW
10:45elbow
11:90elbow
12:4"pipe
Thisdesignusesaseparateinflowandoverflowpipe.
Thisdesignusesthesametankopeningforboththeinflowandoverflow.
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RoofWashers
Rooftopsarepronetocollectleavesanddirt.Theraincarriesallthisdebriswithitasitenters
thegutteranddownspout.Theroofwasherorfirstflushsystemisasimplewaytofilterthe
wateryou
collect.
It
is
aseries
of
pipes
that
storm
water
flows
into
before
entering
the
rain
barrel.Oncetheroofwasherisfull,waterwillbegintofilltherainbarrelwithoutmixingwith
thedirtywatercontainedinthefirstflush.Theappropriatesizeoftheroofwashervaries
dependingonthesizeoftheroof.RefertoSizingofthetankandroofwashersystemonpage
18fordetailsonhowtocalculateroofwashersize.Smallfirstflushsystemscanbeasingle
downwardpipe.However,toaccommodatelargerroofs,firstflushsystemscanbeconstructed
ofmultipledownwardpipes.
Theroofwashermustbeemptied
promptlyafteraraineventandvalve
resetin
the
closed
position
to
be
ready
forthenextrain.Draintheroofwasher
toasafelocation.Includeanotherspigot
orvalveinyourdesigntodrainthefirst
flush.
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AnalternativetothecontainermethodoftheroofwasherisadeviceliketheFlowRate
DiverterbySafeRain.Itconsistsofaplasticballattachedtoaspring.Thetopoftheball
containsascreenandamovabletab.Duringarainfallevent,waterthatentersthepipewill
eitherflowintotheballoronitssides(seepictureonleft).Thepurposeofthescreenontopis
tograduallyallowwatertoentertheball.Oncetheballisfilled,itwillsinkdownandblockthe
drain(see
picture
on
right).
Water
can
then
start
filling
up
the
pipe
and
start
entering
the
tank.
Themoveabletabcontrolstheamountofwaterthatenterstheballbycoveringorexposingthe
screenasdesired.Forexample,largerbarrelsthatrequirelargerroofwashersrequireascreen
thatislessexposed.Largeramountsofwaterwillhavetopassthroughthepipebeforetheball
canbefilled.Theballwillhaveasmalldripholetoslowlyemptyoncetherainhasendedto
thenreturntoitsoriginalpositiontobereadyforthenextrainfall.
Enteringrainwater
willflowintothis
pipe.Somewillenter
theball,
making
it
heavierandsomewill
flowpasttheballand
outofthepipe.
Oncetheballis
saturatedwithwater,
it
will
sink
down
and
blockthepipe.Water
willfillupthepipe
andfinallyenterthe
tank.
Thisdeviceallowstheoverflowpipetobeconnectedtotheroofwasherpipe.
Theballisplacedina3wayteewitha
removablecapsothattheballcanbe
takenout.
Water
gradually
enters
theball
through
this
screen.
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Hereisanideatohelpyoudesignaroofwasherofyourown.
ROOF
WASHER
1:3waytee
2:6pipe
3:90elbow
4:6pipe
5:3waytee
6:6pipe
7:3waytee
8:6pipe
9:drainvalve
INFLOW
10:6x4rubber
coupling
11:
4
pipe
12:45elbow
13:4pipe
14:45elbow
15:4pipe
16:bushing
OVERFLOW
17:bushing
18:90elbow
19:2pipe
20:90elbow
21:2pipe
ANCHORING22:plumbersstrap
Althoughthisrainwaterharvestingsystemhasagoodroofwasherdesign,itdoesnothaveagood
overflowdesign.Excesswaterwillbackupintotheinflowpipebeforetheoverflowpipestarts
working.Theoverflowpipeshouldalsobethesamediameterastheinflowpipetoavoida
bottlenecksituation.
gradually
enters
theball
through
this
screen.
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Overflowpipes
Whentherainbarrelreachesitscapacity,theoverflowpipedischargestheexcesswatersothat
waterwontstartspillingoutfromaroundthelid.Cutaholenearthetopofthebarreland
connectan
overflow
pipe
there.
Be
sure
that
the
overflow
pipe
is
not
directed
toward
water
sensitivestructuresorareaswherewatercancollectanddodamage.Theoverflowpipeshould
bethesamesizeastheinflowpipesothatabottlenecksituationisavoidedduringheavy
rainfalls.
Herearesomeideastohelpyoudesignanoverflowpipeofyourown.
OVERFLOW
1:bushing2:2pipe
3:45elbow
4:45elbow
5:2pipe
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Insteadofdirectingwaterbackintothesewer,youcandirectthewaterintoaraingarden,
gravelfilledtrenchorconnectittoadripirrigationsystem.Overflowcanbeturnedintoworks
ofart.Heretheoverflowisturnedintoasmallwatercourse(seepictureonbelow),which
ultimatelyendsinaraingarden.
OVERFLOW
1:2pipe
2:90elbow
3:2pipe
Theoverflowpipeisconnectedbacktothesewer.
Buildingsystemsclosetothedownspoutrequires
lesspiping.
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Raingardensaredepressedplotsofland(seepicturesbelow).Itshouldbeatthelowestpoint
inthegardensothatwatercanflowthereeasily.Digadeeptrenchandfillitwith5inchesof
gravelforseepage.Coverthisareawithburlapnettingsothatthesoilwillnotsinkdowninto
thegravel.Placeacoupleofinchesofsoilontopandstartplanting.Onlyplantsabletosurvive
bothdryandsaturatedsoilshouldbegrown.Nativeplantsarealsoencouragedbecausethey
aremore
tolerant
of
local
climate
and
soil
conditions.
These
plants
include
wildflowers,
ferns,
shrubsandsmalltrees.9BrooklynBotanicGardenprovidesathoroughlistofraingardenplants
fordifferentregionsontheirwebsiteat:
http://www.bbg.org/gar2/topics/design/2004sp_raingardens.html
Bioswalesarealternativestoraingardens.Theyaredepressionsinthelandscapewith
collectionsofrock,gravelandvegetationthatactasafilterforwater.Theyeffectivelystrain
silt,inorganiccontaminants,organicchemicalsandpathogens.Thelongerthewateristrapped
insidethe
bioswale,
the
easier
it
is
for
pollutants
to
be
trapped.
They
are
most
commonly
found
surroundingaparkinglotsothatoilrunoffcanbefilteredbeforeenteringthesewersystem.10
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Anchoring
Becausetherainbarrelisfairlylightandmaytiporfallwhenitisempty,itisimportantto
anchorthesystemtotheplatformorastructure.Theeasiestmethodtotiedownyoursystem
isto
use
nylon
rope.
Steel
cable
is
also
asolution.
Since
cabling
is
more
complicated,
we
will
illustratethesesteps.
Cutapieceofsteelaircraftcableandslip5cableswedgesinitUsethefirstpieceofcable
swedge(seepicture1)andacrimpingtooltoconnectitintoacircle(2).Itscircumference
shouldbealessthanthecircumferenceoftherainbarrelbutmorethanthatofthelid.Cuttwo
morelongpiecesofsteelcable.Theyshouldbeatleasttwicetheheightoftherainbarrel.Use
onecableandslipitthroughtwoofthemetalcableswedgesthatarealreadyonthecircle.
Makingsurebothlengthsofcableareeven;usethecrimpingtooltosecurethemetalswedges
inplace.Dothesamewiththeothercableandtwometalswedges(3).
Screw
a
metal
eyebolt
into
each
of
the
four
corners
of
your
platform.
Connect
a
turn
buckle
to
eachmetaleyebolt(4).Placetheseriesofcablesontoyourrainbarrel.Thecircleshouldbeon
topoftherainbarrel(5).Thefourhangingendsshouldbefacingeachcorneroftheplatform.
Looptheendsofthecablesintotheturnbuckle(6).Useametalswedgetosecuretheloop.Do
thisforallfourcorners.Finally,twisttheturnbucklesuntilthemetalcablesaretaut(7)tofinish
securingyourrainbarrel(8).
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Forcinderblockplatforms,nailathickwoodenplankontopandusetheeyeboltmethod
mentionedabove.
Prefabricatedsteelbracketsaregenerallyusedtoanchorhorizontaltanks.
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Itisagoodideatoanchorpipesaswell.Ifthepipeishuggingtherainbarrel,anchorthepipeto
thatplatformusingcable(seepicture1),perforatedplumbersstrap(2)orothermethods.
Pipesthat
are
directly
against
the
wall
of
abuilding
can
be
secured
to
the
wall
using
plumbers
strapattachedwithtapconscrews,whichsealtheholedrilledinthewalltoavoidleaks(2).
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DripIrrigation
Dripirrigationsystemsreducewateruse.Smallamountsofwateraresuppliedtothebaseof
plants.Sincethewaterisapplieddirectlytothesoil,ratherthanontotheplant,evaporation
fromleaf
surfaces
is
eliminated.
The
water
is
also
placed
where
it
is
needed
rather
than
sprayed
overtheentiregarden.
Withadripsystem,waterflowsintoaseriesofthinflexiblehoselines.Theseirrigationhoses
havetinyholesatevenintervals.Thesehosesareplacedonthesurfaceorbeneathalayerof
mulch.Whenwaterentersthesystem,itslowlytricklesoutoftheseholesandwaterstheroots
ofplants(seepicturesbelow11).Theoverflowofrainwaterharvestingsystemsissometimes
connectedtothesesmallerpipes.
Tubingcomesinmanysizes(seepicturesbelow12).Itisusedtogetthewaterfromthesource
tothegarden.Avarietyoffittingsareavailabletogoaroundcornersandtoconnectpieces.
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Inmostcases,nospecialtoolsorskillsareneeded.Plasticpipeispunchedwithaninexpensive
tubepunchthatassurestheproperholesize.Spaghettitubessnapintothehole.Nogluingis
required.Becausetheholesaresmall,theycaneasilybepluggedifyouputoneinthewrong
place.
GravityFeed
Drip
Irrigation
Kits
are
used
to
connect
to
rain
barrels
and
rainwater
harvesting
systemswherethewaterpressureislow(seepicturebelow13).Thissystemusessmallinch
valvesinsteadofemitterstoavoidtheproblemofcloggedemitters
DripIrrigationsystemsneedplanning,butareneitherexpensivenordifficulttoinstall.Most
dripirrigationsupplierswillhelpyoudesignasystemtobestmeetyourgardeningneeds.Drip
systemsrequireperiodicmaintenance.Checkregularlyforleaksandbrokenconnections.
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FiltrationSystems
This rainwaterharvestingsystemalreadyhas twomeansof filtration,oneat thegutter (see
picture1)andtheotherattheroofwasher(2).
Thisgutter screen that isputat themouthof thedownspout (see
picture on right) prevents leaves and other large debris from
enteringthesystem.Ifyouwanttobuyafilter,twochoicesareRain
Keeper Downspout filter for smaller roofs and the Rain Keeper
Downspoutcollectionfilterforsmallersystems.RefertoWhereto
obtainsuppliesonpage11formoreinformation.
Thegutterfiltersout
leaves
and
large
debris.
Theroofwasherfiltersoutthe
particulatematterfoundon
rooftops.
1
2
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Treatment
Duringwarmweather,bacteriamaygrowinsidethestoragetank.Organicmatteralsoposesa
problemasalgaeorothercontaminantsmaygrowinstoragetanks.WRGrecommendsaddinga
smallamount
of
chlorine,
in
the
form
of
unscented
household
bleach,
to
your
water
storage
tank.Donotusebleachwithanyadditiveslikefragrancesorsofteners.Alogshouldbekeptto
ensuretheproperadditionofthechemical.Storelogwithbleachcontainer.Pleaseremember
toweargloveswhenhandlingbleach,tostorebleachinacool,dryplaceandtolabelbottle
clearlytoavoidimproperuse.Onthe1stofeachmonth,addasmallamountofbleachtoeach
waterstoragecontainer.Ifthetankisemptiedandrefilledinlessthanonemonthstime,an
applicationofbleachshouldbeaddedtothetankwhenitrefills
TankSize AmountofBleachtoAdd
1000gallons 1/3cup
750gallons 1/4cup
500gallons 3tablespoons
50gallons 2teaspoons
Regularlyemptyingtheroofwasherandtheadditionofasmallamountofbleachtoyourtankwill
ensurethe
water
is
safe
for
watering
vegetables.
The
water
stored
in
the
tanks
is
for
irrigationpurposesonly. Itissafetouseonvegetablesandotherplantsinthegarden,butitisnotsafeto
drink.Thequalityofthiswaterdoesnotcomplywithlocalandnationaldrinkingwaterstandards.
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Aesthetics
Themostbeautifulsystemiscarefullyconstructedandincorporatesacarefullythoughtout,
welldesignedandinstalledplumbingsystem.
Lars
Chellberg,
CENYC
staff
member
Althougharainbarrelisconsideredbysometobeunsightly,itiseasytobeautifyyourrain
waterharvestingsystem.PVCpipesandtankscanbecoveredbyplantsorpainted(seepictures
below).
AgazeboatthisSeattlecommunitygardencoversanundergroundcisternthatstores5,000
gallonsof
collected
rainwater
(see
picture
below).
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Promotingthesustainablepracticeofrainwaterharvestingisalsoimportant.Forexample,NYC
communitygardensuseaThisgardenharvestsrainwatersign(seepictureonright),agood
ideatoputinfrontofyoursystem.Haveprintedinformationforpeopletolearnmoreabout
rainwater
harvesting
like
this
Water
Resources
Group
brochure
(see
picture
on
left).
SometimesitisnecessarytobreaksomebasicRWHrulesforaestheticreasons.Thisrainwater
harvestingsystemhasaninflowpipethatispitchedupwardwhichmeansthatitmustrain
enoughforthewatertofilluptheroofwasherandtheinflowpipebeforeitcanenterthetank.
Thiswasdonesothattheroofwashercouldbepositionedbelowthebrickwallandnot
interferewiththetreelimbortheneighborsviews.
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RoofingMaterial
Rooftopsareessentialtoanyrainwaterharvestingsystem.Populartypesofroofinginclude
corrugatedmetaldecking,shingles,rolledasphaltandcedarshake.
Corrugatedmetaldeckingcancomeintwo
forms zinccoatedorhotdippedgalvanized.
Because,zinccoatedroofsrusteasily,hot
dippedgalvanizedroofsaremorepopular.
Theseroofsareconstructedsimplybynailing
downwithsealingwasherstoyourstructure
orscrewing.Applyguttersealantonanynail
orscrewtomakesurewaterdoesntleak
fromthesespots.Metalroofsprovidegreat
structuralsupportforlongamountsoftime.It
hasthe
highest
efficiency
rate
when
it
comes
torainwaterharvestingbecauseofits
waterproofsurface.Itsonlydownfallisthe
noisefactor.Itgetsveryloudwhenrainwater
clasheswiththerooftop.Itisanidealroofing
materialfornonresidentialstructures.
Shinglesaresmallpiecesofoverlappingwoodorslate.Placeainch
widepieceofplywoodontopofthestructure.Startnailingshingles
inahorizontal,overlappingfashionstartingfromthegutterline.
Workyourwayuptothetopofyourroof,makingsureyournextrow
overlapsthepreviousrow(seepictureonleft14).
Rolled asphaltormodifiedbitumen roofsoccurmost commonlyon flatter rooftops.A large
sheetofasphaltissimplyglueddownwithtarorplastic.Asphaltroofs
can either have a granular surface or a smooth surface. Although
granular surfaces are slightly less efficient in catching rain water
becauseitiseasilytrappedinthepiecesofgroundglass,itispreferred
over smoother roofs.Granular roofswear slowly, resist cutting and
keep UV rays from degrading it. Typically, a few years after the
granularroofisinstalled,itispaintedwithaluminumtolockingrainsthatmayhavefallenloose
(see
picture
on
right
15
).
Cedarshakeorwoodenroofsareinstalledinavertically
overlappingfashion.Woodistheleastefficientincatchingrain
waterbecauseitisporous.However,oncethewoodissaturated,
itwillnolongerabsorbwater(seepictureonleft16).
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45
SeasonalMaintenanceToensureyourhealthandsafetytheWaterResourcesGrouprecommendsthefollowingseasonal
maintenanceschedule
for
keeping
your
rainwater
free
of
contaminants.
Spring
Closespigot Redirectroofwaterfromthedrainpipebackintotankstoragesystembyreplacingthe
inlineplungerorchangingthepositionofthevalve
Cleananywinterdebrisfromgutters,leaderinletsandroof Repairanyleaksinbarrelortanks Inspectandcleanbarreltops Fillsystemwithafewinchesofwatertocheckhoseconnectionsforleaks Inspectrope/cableretainerstoassurethatbarrelsaresecure Besurethatyourtankislabeledwithadonotdrinkthewater signinallappropriate
languages
Tohelpensurethatchildrendonotdrinkthewaterremovethevalvefromspigotandstorewithtools
Summer
Keeptheroof,guttersandleaderinletsclearofdebris,checkmonthly Inspectventsattopofeachbarreltoinsurethattheyarecleanandintact Visityoursystemduringaheavyrainorshortlyaftertocheckforleaksandoverflow
problems.
Anywaterfromtheoverflowsystemshoulddrainwithin24hoursofarainfall;ifpuddlesform,youshouldmovetheoutflowpipetoamoreporoussiteorconsider
installingasmallraingarden
Inspectpipesandconnectorsregularlyforanydamageordisrepair Checkmanwayhatchontopofyourtanktomakesureitissecurelyclosed
Fall
RemoveplungerfromthePVCjointtoredirectwaterintothedrainpipetothesewer Emptywaterfromtheentiresystem roofwasherandtank Openmainvalveofstoragetankandrainbarrels Openvalveonroofwasher. Valvesshouldremainopenallwintertokeepwaterfrom
freezinginsystem
Disconnectleaderfromsystemandreroutewaterasnecessaryforparticularsystem Coveranyopeningsinleaders
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46
LivingwiththeRWHSystemNowthatyouhavebuiltyourrainwaterharvestingsystem,youhavehelpedtoconserveoneof
theEarths
most
valuable
resources.
A
rain
barrel
is
not
something
you
build
and
walk
away
from.Itisimportanttomakesuretherearenoleaksinyourbarrelandtodrainthefirstflush
aftereverystorm.
Remembertodrainyourroofwasherandtankduringthewinterandtotakeoutyour
winteringtee!FreezingwaterwillBREAKthesystem.Thecracksseeninthetwopictures
belowarefromleftoverwaterfreezingandexpanding.
Ifproperlybuiltandmaintained,yourrainwaterharvestingsystemwilllastmanyyears.Even
thesmallest
tanks
will
save
thousands
of
gallons
of
water.
It is essential to learn how tomanage
your water usage. Seventy percent of
residential water use goes to outdoor
activities. One third of that water is
wasted (see diagram on right17).Using
pumpsorsprinklerstowaterplantsare
one of the most inefficient ways to
irrigate.Plantsonlyneedtobewatered
at the roots. Sprinklers relentlessly
wastewaterby randomly shootingoutwater to tree branches or leaves.Drip
irrigation systems with outlets placed
strategicallynexttoplantrootsarethemostefficientwaystoirrigate.
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ExistingRWHSystemsOrganicGardeningMagazinehasbeensponsoringconstructionofrainwaterharvesting
systemsin
community
gardens
since
2007.
Their
Waterworks
Project
funded
30
systems
in
the
past2years.Lookingatexistingrainwaterharvestingsystemsandtalkingtocommunity
gardenersmayassistyouinbuildingyourown.LocationsintheUSAandCanadainclude:
AlemanyFarm SanFrancisco,CA
AshviewCommunityGarden Atlanta,GA
AspenFarms Philadelphia,PA
BoydStreetUrbanFarm Portland,ME
BradnerGardensParkSeattle,WA
BrentwoodCommunityGarden Portland,OR
ChildrenGarden Camden,NJ
CitySeeds
Urban
Farm
St.
Louis,
MO
DiasyFloresNewYork,NY
TheFarmGardenattheEarlyChildhoodEducationCenter Columbus,OH
FremontCommunityGarden Sacramento,CA
TheGardenofDreams NewYork,NY
GlobalGardens Tulsa,OK
GlorylandCommunityGarden,Detroit,MI
GrowingGreenYouthGarden,Buffalo,NY
GuadalupeMontessoriSchool,SilverCity,NM
HopeCommunityGarden Toronto,ONCanada
MarigoldMeadows
Phoenix,
AZ
MasterPeaceYouthandCommunityGarden Riverdale,MD
OurSaviourCommunityGarden Dallas,TX
The1100BlockBergenStreetGarden Brooklyn,NY
UrbanMinistryCenter Charlotte,NC
WasatchCommunityGardens SaltLakeCity,UT
WoodlawnGarden Portland,OR
XochiquetzalPeaceGarden Chicago,IL
Formoreinformationonthesegardens,visittheirwebsiteat:
http://www.organicgardening.com/feature/0,7518,s1210153111X2X34,00.html
ThisguidecanbefoundonCENYCswebsiteat:
http://www.cenyc.org/openspace/rainwater/RWHHowTo.pdf
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10Ways
to
Conserve
Water
1.Turnoffthefaucetwhenbrushingyourteeth,washingyourfaceandshaving.
2.Fixanyleakysinks,toiletsorshowerheads.
3.Washonlyfullloads forclothinganddishes.
4.Donotrunwatertothawmeats.
5.Waterplantsattheroots.
6.Takeshowersinsteadofbaths.
7.Replaceshowerheadsandsinkaeratorswithlowflowones.
8.Useapitchertostorecoldwaterintherefrigeratorinsteadofrunningthetapeverytime.
9.Waterplantsduringearlymorningsandlateafternoonstoreduceevaporation.
10.Donotflushthetoiletunnecessarily.Disposeofbugs,cigarettebuttsandtissuesanother
way.18
19
20
TheWaterResourcesGroup(WRG),acoalitionofNYCgreening&communitygardengroupsis
dedicatedtothepreservationofNYCwaterresourcesthroughgardening,ecologicaldesignand
educationprograms.WRGisinstallingrainwaterharvestingsystemsingardensacrossNYCto
conservewaterandpreventpollution.Formoreinformationonhowyoucanhelpconserve
waterinNewYorkCity,visittheWaterResourcesGroupwebsiteat
www.waterresourcesgroup.org.TheWaterResourcesGroupmeetseverysecondThursdayof
themonthat10a.m.attheCouncilontheEnvironmentofNewYorkCity,51ChambersStreet,
Room214.Allarewelcometoattend.
Ifyouhaveanyquestionsregardingtheconstructionofyourrainwaterharvestingsysteme
mailLenny
Librizzi,
Assistant
Director
of
Open
Space
Greening
at
CENYC
at
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49
1Hasse,Rolf.Rainwaterreservoirsabovegroundstructuresforroofcatchment.WelcometoEnergy.19November2003.20
June2008
2An
introduction
to
rain
water
harvesting.
The
WWW
Virtual
Library
on
Urban
Environmental
Management.
9May
2008.
20
June2008
310,000RainGardens.2008.20June2008
4Water.TheNewYorkObserver.21April2008:G10.
5Anintroductiontorainwaterharvesting.TheWWWVirtualLibraryonUrbanEnvironmentalManagement.9May2008.20
June2008
6RhizomeCollective.EcoWarrior.28Nov2007.11July2008
7OakWhiskeyBarrel.RainBarrelbyAaron.2003.11July2008
8 Products.RainDropsCisternsRainwaterHarvestingandStorage.23June2008.11July2008
9RainGarden.Wikipedia:TheFreeEncyclopedia.12June2008.20June2008
10 Bioswales.Wikipedia:TheFreeEncyclopedia.3April2008.20June2008
11ChapinWatermaticsInc.11July2008
12Dripdepot.11July2008
13Dripdepot.11July2008
14Roofing.
Sam
Siding
Home
Improvement.
20
June
2008
15LexisCoatings.20June2008
16Cedar.HynesHomeImprovement:TheSignofQuality.11July2008.
17HydrapureWaterSolutions.Hydrapure.11July2008.
18Lenz,Ericka.10easywaystoconservewater.GaiamLife YourGuidetoaBetterLife.20June2008
1910waystoconservewater.EtowahWaterandSewerAuthority.2February2008.2008June2008
20TenWaysToConserveWaterAroundTheHouseAndHelpTheEnvironment.TheGoodHuman.2July2007.20June2008.
ThismanualwasputtogetherbyJuliaLeung,LennyLibrizzi,AssistantDirectorofOpenSpace
GreeningatCENYCandLarsChellberg.
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Afterreadingthismanual,pleasefilloutthisfeedbackformandmailitto:
CouncilontheEnvironmentofNYC
51ChambersStreet,Room228
NewYork,
NY
10007
Onascaleof110,10beingthemostagreeable,1beingtheleast,assessthefollowing
statements:
Thismanualiseasytounderstand.1 2 3 4 5 6 7 8 9 10
Thismanualcontainsclearinstructions.1 2 3 4 5 6 7 8 9 10
Thismanualhelpedyoumakeyourrainwaterharvestingsystem.1 2 3 4 5 6 7 8 9 10
Youunderstandhowarainwaterharvestingsystemworks.1 2 3 4 5 6 7 8 9 10
Youarenolongerinterestedinrainwaterharvesting.1 2 3 4 5 6 7 8 9 10
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1
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6
7
8
9
10
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