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Australian Capital Territory
Rainwater tanks
Guidelines for residential properties in Canberra
Reprinted June 2006
�
Contents
Foreword 3
Commonly asked questions
Whyinstallarainwatertank? 3
HowcanIuserainwater? 4
HowbigatankdoIneed? 4
CanIdisconnectfromtheACTEWwatermains? 4
Whattypeofrainwatertankisbestforme? 5
Howmuchwillitcost? 5
Arethereanyfinancialincentives? 5
WillIpaylessonmywateraccount? 6
WhatworkcanIdowithoutaplumbingorelectricitylicence? 6
Arethereapprovalcosts? 6
Istankwatersafetodrink? 6
ShouldIaddfluoride? 7
ShouldIusekerosenetocontrolmosquitoes? 7
DoIneedtofiltertankwater? 7
Rainwater assembly options
Illustrations 8-�0
Installation requirements
Rainwatertankbases ��
Coversandlids ��
Screensandstrainers ��
Firstflushrainwaterdiverter �2
Plumbingpipesandfittings �2
Lightproofing �2
Pumps �2
2
Top-upfacility �3
Overflow �3
Maintenance and system management
Drinking water safety
Healthconsiderations �4
Disinfection �5
Roofmaterials �5
Leadflashing �5
Paintsandcoatings �5
Regulations
Planningandbuildingapprovals �6
Buildingwithineasementsornearutilityassets �7
Plumbingapprovals �7
Plumbingrequirements �7
Rainwaterplumbingmaterialsandlabelling �8
Proximitytootherservices �9
Backflowprevention �9-20
Contact details 21
References 21
Appendix A 22
3
Foreword
TheACTGovernmentiscommittedtothewiseuseoftheregion’swater.Thestrategyforsustainablewaterresourcemanagement,'Think water, act water',providesaclearvisionandarangeofinitiativesforthesustainableuseofwaterresources.ItsetstargetstoreduceCanberra'spercapitamainswaterconsumptionby�2percentby20�3and25percentby2023.OneproposalistopromotetheuseofrainwatertankstohelpreducethepercapitademandontheACTEWwaternetwork.
ThisRainwaterTankGuidehasbeenpreparedinpartnershipbetweenActewAGL,EnvironmentACT,theACTPlanningandLandAuthorityandACTHealthandprovidesguidanceontheinstallationofrainwatertanksinresidentialproperties.
Commonly asked questions
Why install a rainwater tank?
Rainwatertankscanmakeanimportantcontributiontowardsreducingthedemandourhomesmakeondamstorages.Rainwatertankscanalsohelpslowtheflowofstormwaterfromoururbanenvironmentintolocalcreeksandrivers.Byusingrainwateryoucanalsomakesavingsonyourwateraccount.
Theseguidelineshavebeenpreparedtohelpyouunderstandthekeyissuesthatneedtobestudiedwhenplanningasuccessfultankinstallation.Subjectscoveredinclude:
• howmuchwatertostore,• healthandsafety,• regulationsand• installationrequirements.
AlltheessentialrequirementsofActewAGL,ACTHealth,theACTPlanningandLandAuthorityandEnvironmentACThavebeenincludedtomakeyourinvestigationseasier.
However,whilethisinformationwascorrectatthetimeofprinting,requirementscanchange.Youareadviseditisyourresponsibilitytoensureyouareawareofuptodatelegislationandregulations.Youshouldcontactrelevantagencieslistedonpage2�toensureyouhavethelatestinformation.
4
How can I use rainwater?
Ataponasimplerainwatertankcan:
• supplyirrigationdrippersorasoakerhose,• fillabuckettowashacar,• top-upaswimmingpooland• fillanornamentalpond.
Withadditionalplumbingarainwatertankcansupplywaterto:
• ahose,• irrigationspraysand• aflushingtoilet.
Withcarefulcontrolofwaterqualityarainwatertankcanalsobeusedto:
• fillawashingmachine,• runshowersandbathsand• providesafedrinkingwater.
How big a tank do I need?
Estimatingthesizeofatankrequiresacombinationofexperienceandcalculation.Rainfallisvariableanddemandwillchangewiththeseasonsandtheneedsoftheresident.Inaddition,thesizeoftherainwatertankwilldependon:
• howmuchrainfallseachyear,• theareaofroofavailabletocapturetherain,• howyouplantousetherainwater,• thenumberofpeoplelivinginyourhouse,• thecurrentwaterusagerateand• availablespacetoinstallthetank.
Youcanestimateyouryearlywatersavingswiththecalculatoratwww.thinkwater.act.gov.au/calculators/water_calculators.shtmloratAppendixAofthisbook.Theexperienceofyourlocalrainwatertanksupplierwillalsobeinvaluable.
Can I disconnect from the ACTEW water mains?
Makingyourhomeself-sufficientandindependentfromtheACTEWnetworksupplyrequiresalargecontributingroofareaandsubstantialtankcapacity(probablygreaterthan�00,000litresforanaveragehouse).Canberrahasavariablerainfallandissubjecttodrought,sorigorouswatersavinghabitsarerequiredifyouwantyourhouseholdtobeself-sufficient.Eventhenthereisnoguaranteethatyouwouldneverrunoutofwater.
5
ActewAGLcandisconnectyourmainspressurewatersupplyinaccordancewiththestandardscheduleofprices.Afterdisconnectionyouwillnotbebilledforwaterusagechargesbutyouwillhavetopayanetworkavailabilitycharge,sothereisnofinancialbenefitindisconnecting.Keepingthenetworksupplyforemergenciesortop-upisausefulsafeguard.
What type of rainwater tank is best for me?
Mostresidentialrainwatertanksaremadefromplastic,fibreglass,concrete,corrugatedgalvanisedsteelorcorrugatedsteellinedwithplastic.
Almostanytankmaterialcanbeusedtostorewaterforirrigationortoiletflushing.
Tanksusedfordrinking,foodpreparation,washingclothes,showersorbathingshouldbemadefrom,orlinedwith,adrink-safe(foodgrade)material.
Yourtankmanufacturercanadviseaboutthebestmaterialandmosteconomicalsolutionforaboveorbelowgroundtanks.
How much will it cost?
Rainwatertankpricesvaryaccordingtosize,material,finish,strengthandquality.Itisworthcomparingpricesfromseveralsuppliers.
Otherinstallationcostswillvaryaccordingtothecomplexityofyoursystembutmayinclude:
• transportation,• alterationtoguttersanddownpipes,• tankstandfoundationwork,• afirstflushrainwaterdiverter,• inletandoverflowpipeinsectscreens,• plumbingpipesandfittings,• engagingalicensedplumberforhouseholdplumbing,• watertop-upfacility,• apumptoincreasepressure,andflowratesand• associatedelectricalworks.
Are there any financial incentives?
Financialincentivesintheformofrebatesmaybeavailabletoassistyourpurchaseofarainwatertank.ThedetailsofanycurrentrebateprogramsareavailablefromtheThinkwaterwebsite:www.thinkwater.act.gov.au
6
Will I pay less on my water account?
YoucanexpecttomakesomesavingsonyourActewAGLwateraccountifyouusearainwatertank.However,youmaywishtoestimatewhatthesesavingsarelikelytobebeforeinstallingarainwatersystem.
What work can I do without a plumbing or electricity licence?
Taking due care, a handy person can install:
• tanksandstands,• irrigationsystemsfromadedicatedtank,• apressureboostingpumpusedsolelyforirrigationand• rainwaterguttering,downpipesandstormwaterdrains. A licensed plumber must be engaged to install:
• rainwaterplumbingpipesprovidingwatertothehouse,• pressureboostingpumpsforhouseholdrainwaterplumbingand• tanktop-upsystems(fedfromthecitywatersupply).
Forfurtherdetailseethesectionon‘Regulations’.
A licensed electrician must be engaged to modify or install:
• poweroutletsand• fixedwiringtopumpsorelectricalappliances.
Forfurtherdetailseethesectionon‘Regulations’.
Are there approval costs?
Youmaybesubjecttogovernmentchargesforplanning,buildingandplumbingapprovals.Governmentplumbingchargesmaybeincludedinyourplumber’saccount.DetailsareavailableinthefeesandchargesbookletavailableattheACTPlanningandLandAuthorityCustomerServiceCentre.
Is tankwater safe to drink?
TheuseoftankwaterfordrinkingorfoodpreparationisnotrecommendedwherethereisapotablenetworksupplyavailablewhichmeetstheAustralianDrinkingWaterGuidelines.Ifyouchoosetoinstallarainwatertanktoprovidedrinkingwater,youshouldcontactACTHealthforadviceandfollowthesuggestionsincludedinthesectionon'drinkingwatersafety'.
7
Should I add fluoride?
Rainwaterdoesnotcontainfluoride.Youshouldnotaddfluoridedirectlytotherainwatertank,asitisverydifficulttocontrolthecorrectdosagerate.Talktoyourdentistaboutsubstitutes.
Should I use kerosene to control mosquitoes?
Lowoxygenlevelsintankwater,causedbyexcessivesludge,willattractmosquitoes.Youmayhaveheardthatateaspoonofkerosenepouredontothesurfaceoftank-waterwillstopmosquitoesfrombreeding.Thisistrue,howeverthereisnoneedtousekeroseneasfineinsectscreensorfinemeshscreensproperlyinstalledoninletandoverflowpointswillpreventmosquitoesenteringthetank.Undernocircumstancesshouldkerosenebeusedifthetankisfordrinkingwater.Kerosenemayalsobedamagingtoplasticor‘Aquaplate’coatings.
Do I need to filter tankwater?
Sedimentandorganicmaterialaccumulatesinrainwatertanks.Afilterontheirrigationsystemcanhelppreventsprinklerheadsfrombecomingcloggedwithsludge.
Afiltermaybeinstalledatthekitchensinktoremoveimpuritiesfromdrinkingwater,howevertheunitshouldbemaintainedinaccordancewiththemanufacturer’sinstructionstopreventthefilterbecomingasourceofcontamination.
8
Rainwater assembly options
Thefollowingassemblyoptionsillustratesomebasicrainwatertankandplumbingconfigurations.
Basic tank
Thesimplestinstallationisarainwatertankonastandwithasimpletapoutletforfillingajugorbucket.
Tap with basic irrigation system
Adedicatedabove-groundtankcanrunasoakerhoseoradrippersystem(bygravity)forthegardenorvegetablepatch.
9
Pump connected to irrigation system with sprinklers
Apumpmaybenecessarytoprovidethepressurerequiredforirrigationsprinklersormicro-sprays.Therainwatertankmaybeaboveorbelowtheground.*
Tank connected to toilets, washing machines and diswashers
Toilets,washingmachinesordishwasherscanusetankwater.Apumpisusuallynecessarytoboostpressureandflow.Therainwatertankmaybeaboveorbelowtheground.*
*Undergroundtankscanbeusedforirrigationsprinklersandhouseholdappliancesbutusuallywillneedapumpto
boostpressureandflowrates.
�0
Plumbingconsiderationsincludethefollowing.
Washing machine options
Washingmachinesusuallyhavehotandcoldwaterinlethoses.Thecoldwaterhosecanbeconnectedtoarainwateroutletormovedtothemains-waterifthetankrunsdry.Ifyouchoosetopermanentlyconnectthewashingmachinetoarainwateroutletitmaybenecessarytoinstallamainstop-upvalveatthetanktopreventthetankfromrunningdry.
Dishwasher options
Under-benchdishwashersareusuallyconnectedtothehotwatersupply.Ifthehotinlethoseisconnectedtoacoldrainwateroutlet,cycletimeswillbelonger.Ifadishwasherispermanentlyconnectedtotherainwateroutlet,youmayrequireamainstop-upvalveatthetanktomakesureitdoesnotrundry.
Toilet cistern options
Toiletcisternscanbeconnectedtoadedicatedrainwateroutlet,howeveryoumayneedamainstop-upvalveatthetanktomakesurethetankdoesnotrundry.Itisalsopossibletoconnectacisterntobothmains-waterandtankwateroutlets,providedthecisternhastwocisternvalves(withair-gapbackflowprevention).
Toilet cistern assembly showing rainwater and mains-water connection
��
Installation requirements
Herearesomeessentialsthatneedtobeaddressedwheninstallingarainwatertank:
Rainwater tank bases
Mostmetalorplastictanksmusthaveastandorbasetocarrythecombinedweightofthetankandwater.Mostflat-bottomedtanksarenotabletocarrytheheavyloadofwaterwithoutthesupportofastrong,levelandcontinuousbase.
Whenarainwatertankisfull,everykilolitreofwaterweighs�000kilograms(onetonne)soforsafetyitisimportanttoconstructatankstandthatisstrongandstable.Whenarainwatertankisemptyitcanbeblownoverbystrongwinds,somakesureyourtankisadequatelysecuredtothestand.Lightweightstandsshouldbesecurelyfixedtoaheavyfooting.
Ifyouareintendingtouseapumptodistributethewater,therainwatertankcanbeatalmostanylevel.Ifyouwishtofeedthewaterbygravityitisusuallynecessarytoelevatetherainwatertankonasturdystand.
Topreventexternalcorrosion,theundersideofmetalrainwatertanksshouldbekeptabovethegroundandsitonaself-drainingbase.
Undergroundrainwatertanksmustbesealedagainsttheentryofsurfacerun-off,groundwaterandleakingsanitarydrainsthatmaycontainpesticides,fertiliserandanimal(orhuman)faecalmaterial.
Undergroundtankswillfloatifsurroundedbywater.Makesuretheholeiswelldrained.Seekengineeringadviceifyouareuncertainaboutfoundationorgroundwaterconditions.
Careshouldbetakennottoplacerainwatertanksinsidethedrip-lineofatreecanopy.Rootgrowthcandamagethebaseoftanks.Treesmayfailtothriveifraincannotgettotheroots.
Covers and lids
Arainwatertankshouldhaveanimperviouscovertopreventtheentryofdust,leaves,pollens,debris,vermin,mosquitoes,birds,animalsandinsects.
Itisessentialtosealaccesshatcheswithstrong,close-fitting,childprooflids.
Screens and strainers
Theinlettotherainwatertankshouldincorporateameshscreenorstrainertopreventtheentryofliveinsectsandtocatchleavesandundesirableroofdeposits.Ameshwithopeningssmallerthanonemillimetreisveryeffectiveagainstmosquitoes.
Thetankoverflowshouldalsobeprotectedwithaninsect-proofmesh.
�2
First flush rainwater diverter
Foraddedprotectiona‘firstflush’rainwaterdivertercanbeinstalledtodivertthe‘firstflush’ofrain(containingroofdust,leaves,droppings,etc.)tothestormwaterandthendirectcleanwaterintotherainwatertank.
Fabricated first flush Commercial first flush
Firstflushdiversionvalvescanbefabricatedusingplumbingfittingsorpurchasedasacompletecommercialunit.
Plumbing pipes and fittings
Tankwatertendstobeacidicandcancorrodemetal.Itisadvisable,especiallyinnewinstallations,touse‘rainwater-standard’plasticpipesandfittings.Seethesectionon‘Rainwaterplumbingmaterialsandlabelling’.
Light proofing
Tanks,covers,plumbingpipesandfittingsshouldbelightprooftominimisedaylightpenetrationandalgalgrowthinthewater.
Pumps
Iftherainwatertankcannotbeelevatedsufficientlytogiveadequatepressuretoappliances,itmaybenecessarytoinstallapressure-boostingpump.Thefloatvalvesintoiletcisterns,irrigationsprinklersandthesolenoidvalvesinwashingmachines(ordishwashers)maynotoperateeffectivelywithoutadequatepressure.Thesizeofpumpwillvaryaccordingtotheheightofthetank,heightoftheappliance,diameterofplumbingpipesandtheflowrequirementsofappliances.Theservicesofahydraulicspecialistand/orpumpsuppliermayberequired.
�3
Top-up facility
Iftankwateristhesolesourceofsupplyforselectedtapsorappliances,youmayneedtotop-upthetankfromthedrinkingwaternetworkduringdryperiods.Top-upscanbedonewithahoseorapermanentoverheadfillingtapcomplyingwithACTPlanningandLandAuthorityplumbingregulations.Thetop-upfacilityforrainwatertanksshouldcomplywithAS/NZS3500Part�.
Whentopping-up,remember:
• hosesmustnotbeimmersedinthetankwater(seethesectionon‘backflowprevention’),
• onlytop-upalittle,perhaps�0percent(leavingspacefortherainwhenitcomes)and
• duringwaterrestrictions,topping-upmaybebannedforsomeirrigationsystemsorrequireanexemptionforotheractivities.
Overflow
AlthoughitiscommonpracticeinCanberratoconnectroofdownpipesandtankoverflowstothehouseholdstormwaterdrainagesystem,thereisnoregulatoryrequirementtodoso.Itispermissibletospilltheoverflowontotheyard,howeveritisnotpermissibletoletanyofthatstormwaterrunoutsidetheboundariesofyourproperty.Itisalsoillegaltoconnectthetankoverflowtodischargeintotheseweragenetwork.
Greatcareshouldbetakennottoletstormwaterpondunderfloorsorfloodaroundthefoundationsofbuildings.Highhumiditycanrottimberfloors,corrodemetalfittingsandpromotethecorrosionofreinforcementinconcreteslabs.Anincreaseinfoundationmoisturecontent,especiallyinclaysoils,cancausecrackinginhousewallsorevenoverturnretainingwalls.
�4
Maintenance and system management
Rainwatersystemsneedtobemaintainedregularlytoensurethatthewaterqualityisatitsbestforthepurposeyouintend.Tomaintainyourrainwatertankyoushouldensurethat:
• allthecomponentsarekeptingoodrepairandfreeofcorrosion,
• guttersarecleanedregularlytoremoveleaves,debrisandanimaldroppings(gutterguardscanhelpreducethebuild-upofleavesbutrequireregularchecking),
• rainwaterisnotpondinginroofgutters,
• therainwatertank’sinletandoverflowscreensarecheckedandcleanedregularly,
• the‘firstflush’waterdiverteriscleanedandflushedperiodically,
• therainwatertankisdesludgedifthebuild-upiscloggingfiltersorcolouringthewater,
• therainwatertankroofisfreeofcorrosionand
• theaccesshatchissecure.
Drinking water safety
Health considerations
Inurbanareasaccesstoareticulatedpotablewatersupplyremainsthemostsafeandreliablesourceofdrinkingwaterforthecommunity.Theuseofarainwatertankfordrinkingpurposesisnotrecommendedwhereareticulatedsupplyisavailable.Inurbanareasairbornecontaminantsandotherpollutantsmayfindtheirwayintorainwatertanks.
Ifyouchoosetouserainwaterfordrinking,foodpreparationorpersonalhygiene,itisimportanttominimisetheriskofcontamination.Pleasetakethefollowingprecautions:
• screenallopeningstopreventleaves,insects,birds,possums,frogs,faecesandotherforeignmaterialfromgettingintothetank,
• therooffinish,gutters,down-pipes,tankandplumbingsystemmustbemade‘drinkingwatersafe’—ifindoubtgetaclearancefromtheproduct/paintmanufacturer,
• installa‘firstflush’devicetodivertthefirstflushofdirtyroofwaterawayfromthetank,
• flushstagnantmainsorrainwaterfrommainsorrainwaterplumingpipesiftheyhavebeenunusedforalongtime,
• donotletcontaminatedgroundwaterinfliltrateundergroundwatertanks,
• checkandmaintainthesystemregularly,and
• contactACTHealthifyouhaveanyhealthconcerns.
�5
Disinfection
Regulardisinfectionofrainwaterheldindomestictanksisnotconsiderednecessaryinmostcasesandisgenerallyonlyrecommendedasaremedialaction.
Asthemicrobiologicalqualityofthewaterattimesmaynotbeasgoodasreticulatedwatersupplies,peoplesuchastheveryyoungorelderly,orimmuno-compromisedshouldconsiderboilingthewaterbeforeconsumptionorforuseinfoodpreparation.Heatingandholdingtherainwateratarollingboilforoneminuteormorewillkillanyharmfulmicroorganisms.
ChlorinationiseffectiveagainstharmfulbacteriaandmanyvirusesbuthaslimitedeffectsagainstprotozoasuchasGiardia andCryptosporidium.Itshouldbenotedthattheeffectivenessofchlorineisshortlivedanditwillonlyactonwhatisinthetankatthetimeofdosing.
Iftherainwaterissuspectedasbeingapossiblecauseofgastricillness,thentherainwatertankandcatchmentareashouldbeinspectedandappropriateremedialactiontaken.
Roof materials
Roofsconstructedofcementorterracottatiles,Colorbond®,galvanisedsteel,Zincalume®,fibrouscement,polycarbonate,fibreglassorslateshouldbesuitableforthecollectionofdrinkingwater.Ifindoubtgetaclearancefromthemanufacturer.
Steelcladdingsshouldbefreeofcorrosion.
Lead flashing
Asaprecautionleadflashingshouldnotbeonthosepartsoftheroofusedasadrinkingwatercatchmentarea.Inthecaseofanexistingroof,leadflashingshouldbereplacedifpossible,althoughitmaybepossibletocoattheflashingwithsuitableroofpaint.Askyourpaintsupplierforadvice.
Paints and coatings
Beforepurchasingmaterialorpaintforroofsusedtocollectdrinkingwater,readandobservethemanufacturer’srecommendations.
�6
Regulations
ThissectionsetsoutACTPlanningandLandAuthorityandActewAGLrequirementsfortheinstallationofrainwatertanks.
Planning and building approvals
TheACTPlanningandLandAuthorityrequiresthelocation,sizeandinstallationofrainwatertankstobeappropriatetothestreetscapecharacterandnottoimpactontheamenityofresidents.
Iftherainwatertankisforwardofthefrontbuildinglineitisusuallyrequired:
• tohaveaminimumsetbackfromthefrontboundarynotlessthan50%oftheminimumsetbackapplicabletothatproperty,
• nottoreduceviewstothestreetfromwindows,
• nottoreducesolaraccessordaylighttohabitablerooms,and
• tobescreenedinasensitivemannerwithappropriateshrubberyorwalling.
ResidentialsetbacksarepublishedinPlanD2.�ofAppendix���.�(ResidentialDesign&SitingCodeforSingleDwellingintheACT)orAppendix���.2(ResidentialDesign&SitingCodeforMulti-DwellingintheACT).
Theinstallationofarainwatertankrequiresplanningapproval(andperhapsbuildingapproval)ifitis:
• infrontoftheresidence,
• morethan�7,000litrescapacity,
• locatedinaheritagelistedarea,
• higherthan2.4metresabovenaturalgroundleveland
• madeofreflective,whiteoroff-whitematerial.
Inaddition,ifthetankistobeinstalledwithin3metresoftherearboundaryand/or�.5metresofasideboundary,planningapprovalmustbesoughtifthereisanotherclass�0structureontheboundary.(Class�0structuresincludepoolsandwatertanks.)
Fordesignandsitingadviceinaheritagearea,[email protected].
TheACTPlanningandLandAuthoritywilltellyouifitisalsonecessarytoobtainbuildingapprovalfromaprivatecertifier.
�7
Building within easements or near utility assets
Rainwatertankscannotbeconstructedwithineasementsorwithinthe‘protectionenvelope’requiredforutilityservicesdescribedinRule2ofActewAGL’s‘BuildingoverornearACTEWCorporationwaterandsewerpipes’brochure.PermissibledistancesbetweentanksandoverheadelectricitymainsaresetoutinSection�9ofthe‘UtilityNetworks(PublicSafety)Regulations’,andvaryfrombetween0.�metreto4metres,dependingonthevoltageoftheaerialcableconductor.Thelocationofnaturalgas,stormwaterandcommunicationassetscanbeobtainedbyphoning‘Dial-Before-You-Dig’on��00.
Plumbing approvals
Theinstallationofarainwatertankdoesnotrequireplumbingapprovalifthetankis:
• freestanding,
• tobeusedonlyforgardenorlawnirrigationand
• notdeliveringrainwatertotaps,fixturesorappliancesinthehouse.
AllotherinstallationsrequireplumbingapprovalandcompliancewithAS/NZS3500Section�4Installation of water supply systems from rainwater tanks.
Plumbing requirements
BelowisasummaryofAS/NZS3500Section�4requirementsforinstallingarainwatertankonaresidentialproperty.
�) Allplumbedpipingsystemsdeliveringrainwatertotaps,fixturesorappliancesinthehousemustbeinstalledbyalicensedplumberandmeettherequirementsofACTplumbinglegislationandAS/NZS3500.
2) AsageneralruletheremustbenodirectconnectionbetweenarainwatertankplumbingsystemandpotablewaterplumbingpipesservedbyActewAGL’sreticulateddrinkingwaternetwork(inspecialcasesinterconnectionmaybepermittediftheriskislowandadditionalfailsafeengineeringcontrolsareevaluatedandapprovedbytheACTPlanningandLandAuthorityandActewAGL).
3) Whereahigherriskofcontaminationofthewatersupplyisidentifiedtheplumbingregulator,theACTPlanningandLandAuthority,orActewAGLmayrequirethepropertyownertoinstallahigherhazardbackflowpreventiondeviceatthepropertyowner’scost.Generalrequirementscanbefoundlaterinthisbrochureunder‘BackflowPrevention’.
4) Rainwaterplumbingworkservinginternaltaps,fixturesorappliances,mustbenotifiedtotheACTPlanningandLandAuthorityusinga‘StartofWork'noticebeforeworkistocommence.
5) Atop-upfacility(drawingwaterfromtheACTEWnetwork)requiresa‘StartofWork'notice.
�8
6) Theplumbermustarrangeforalldrinking-waterandrainwaterplumbingworktobeinspectedbytheACTPlanningandLandAuthority.
7) TheplumbermustsubmitaCertificateofCompliancetotheACTPlanningandLandAuthorityandthecustomeratcompletionofthework.
Rainwater plumbing materials and labelling
Plumbingforarainwatersystemmustuseapprovedmaterialsandbelabelledtodistinguishitfromplumbingusedfor(ACTEW)drinkingwater.AllpipesthatmaybeincontactwithrainwatershouldcomplywithAS/NZS4020.
MaterialsusedinplumbingforarainwatertankmustcomplywithAS/NZS3500‘Water supply – Acceptable Solutions’- Section 2 ‘Materials and Products’.Complyingproductsaremarkedwiththe‘AustralianStandardMark’“5ticks”,“W”forthewatermarkor“T”fortypetested.
Allabovegroundrainwaterservicepipesmustbeclearlymarkedatintervalsnotexceeding�metrewiththecontrastingcolouredwording‘RAINWATER’.Wateroutletsshallbeidentifiedas‘RAINWATER’withalabelorarainwatertapidentifiedbyagreencolouredindicatorwiththeletters‘RW’.Thispipelabellingcanbeachievedforabovegroundpipesbyusingadhesivepipemarkers(inaccordancewithAS/NZS�345).
Allbelowgroundrainwaterservicepipesmustbeclearlylabelled‘rainwater’continuouslyalongtheirlength,‘RAINWATER’identificationtapeforbelowgroundpipesshouldbe75millimetreswideandbeinstalledonthetopoftherainwaterpipeline,runninglongitudinallyandfastenedtothepipeatintervalsofnotmorethan3metres.Thiscanbedoneforbelowgroundpipesbyusingidentificationtape(madeinaccordancewithAS/NZS2648).
Rainwater labels
�9
Everyrainwatertankoutletmustbelabelled‘Rainwater’onapermanentsign.
Proximity to other services
RainwaterpipesmustnotbeinstalledinsidethepipeprotectionenvelopeofanyACTEWwaterorseweragemainorActewAGLelectricitymains.Allabovegroundrainwaterpipesmustbelocated�00millimetresfromanydrinkingwaterservice.Allbelowgroundrainwaterpipesmustbelocated300millimetresfromanydrinkingwaterservice.
Backflow prevention
Wherethereisthepotentialforthereverseflowofpollutedwatertocontaminateadrinkingwatersupply,anapprovedbackflowpreventiondevicemustbeinstalled.
Standards
AS/NZS3500PlumbingandDrainagePart�Waterservicessection�4“Installation of Water Supply Systems from Rainwater Tanks”Table�4.�,setouttheminimumrequirementsfortheinstallationofbackflowpreventiondevicesforzoneprotectionforburied,partlyburiedandabovegroundrainwatertanksinresidentialandcommercialapplications.
Table�onpage20suppliesasummaryofbackflowprotectionrequirementsforzoneandcontainmentprotection.
20
Type of installation Hazard ratingAS/NZS 3500
Containment protection at the
property boundary(Watermeter)
Individual or Zone protection at the
tank top up
Residential
Integrated plumbing (externalandinternal)
Underground(fullyburiedtank)
Medium Testabledevice Testabledeviceorairgap
Underground(partlyburied)
Low Non-testabledeviceor
Water meter with integral backflow
prevention*
Non-testabledeviceorairgap
Abovegroundtank Low Non-testabledeviceor
Water meter with integral backflow
prevention*
Non-testabledeviceorairgap
Residential
External rainwater plumbing only
Aboveorbelowground
Externalhosetapsandirrigationonly.
Noconnectiontothenetworkutilityoperator
watersupply
Low Non-testabledeviceor
Water meter with integral backflow
prevention*
Notapplicable
Commercial Application
(externalandinternal)
Aboveorbelowgroundrainwatertanks
Medium Testabledevice Testabledevice
Table 1
* ActewAGL approved water meters.
2�
Contact details
ACT Planning and Land Authority
Development(designandsiting)enquiries�6ChallisStreet,DicksonTelephone-6207�93� 8.30amto4.30pmweekdays
Buildingandplumbingenquiries�6ChallisStreet,DicksonTelephone-6207626� 8.30amto4.30pmweekdaysorCnrLysaghtandHoskinsStreets,MitchellTelephone-62076262 8.30amto4.30pmweekdayswww.actpla.act.gov.au
Environment ACTMacarthurHouse�2WattleStreet,LynehamTelephone-62079777 8.30amto5pmweekdayswww.environment.act.gov.au
ACT Health HealthProtectionServiceTelephone-6205�700 8.30amto4.30pmweekdayswww.health.act.gov.au
Heritage ACT MacarthurHouse�2WattleStreet,LynehamTelephone–62079777 8.30amto5.00pmweekdaysEmail:[email protected]
ActewAGL Water Division�2HoskinsStreet,MitchellTelephone-62483555 8:30to5:00pmweekdayswww.actewagl.com.au
Dial-Before-You-DigTelephone��008.00amto5.00pm
References
NationalEnvironmentalHealthForum,‘Guidance on the use of rainwater tanks’.
NationalEnvironmentalHealthForumMonographs,WaterseriesNo3�998,DavidACunliffe.www.health.nsw.gov.au/public-health/ehd/water/rainwater.html
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Appendix A – Determining rainwater tank size
Thechartsandtablesinthisappendixwillassistyoutochoosethesizeofrainwatertankbestsuitedtoyourneeds.TheyfactorinCanberra’srainfall,youravailableroofareaandtypicalquantitiesusedforgardenwatering,laundryuseandtoiletflushing.
Thefollowingprinciplesapplywhencalculatingthebesttanksizeforyou:
• Thelargertheroofareaconnectedtothetank,themorewatercollected. Forexample,atankconnectedtoonedownpipeonahousewithfourdownpipes canonlycaptureapproximately25%oftherainthatfallsontheroof.
Alldownpipesshouldbeconnectedtogetthemaximumbenefit.
• Themoreusesmadeofyourtankwater,thegreaterquantityofwateravailableovertime.Forexample,ifyouonlyusetankwateronthegarden,verylittlewillbeusedinthecoldermonths,sothetankislikelytofillandoverflow.Year-roundtoiletflushingorlaunderingreducesthelikelihoodofoverflowlossesandincreasesthetotalamountofwateryouwillcollect.
• Canberra’srainfallvaries,withlongdroughtperiods,sotheamountofwater collectedwillvaryfromyeartoyear.Evenverylargetankscanrundry.
Thecharts(onpages25-27)showtheaverageamountofwaterinkilolitres(kl)youcanexpecttobeabletouseeachyearfromatank.Thiswillvaryfromyeartoyearandhouseholdtohousehold.ThechartsarebasedonwaterconsumptionforanaverageCanberradetachedhouse(showninTable�).
Table 1. Average Consumption per Household
WaterUse Amount(kl/year) %ofTotalUse
Gardenwatering&otheroutdooruse �4� 43%
Toiletflushing 60 �8%
Laundry 43 �3%
Otherinternaluses(kitchen,shower,bath,etc.) 86 26%
Total 330 �00%
Comparethesefigureswithyourwateraccountsforthelastfewyearstogetabetterideaofyourownwaterconsumption.
Thefollowingexamplesshowhowtousethechartstodecidewhatsizetankwillgiveyouthebestreturnonyourinvestment.Ifyouhavedifficultyunderstandingtheseexamples,oryouwanttoexamineotheroptions,pleasetalktoActewAGL,theACTPlanningandLandAuthority,EnvironmentACT,oraskyourlocaltankmanufacturerforadvice.
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Example 1
“Myroofis200squaremetres(sqm)andhasfourdownpipeseachdrainingonequarteroftheroof.WhatsizetankshouldIinstallandhowmuchofmyroofshouldIconnecttothetankforgardenwatering,toiletflushingandawashingmachine?”
Step�.OnChart5-Gardenwatering,toiletflushingandwashingmachine(page27)selecttheverticallineforthedifferentroofareas(forexample,fourdownpipes=200sqm).Markwhereitcrosseseach‘tanksize’curve.Readtheavailablewaterfromtheverticalaxis.Recordthesenumbersintoatable,forexample,table2below.
Table 2. Water Available (from Chart 5)
Tanksize(litres)
Wateravailablefromtankinkilolitresperyear
�downpipe 2downpipes 3downpipes 4downpipes
Roofarea:50sqm
Roofarea:�00sqm
Roofarea:�50sqm
Roofarea:200sqm
500 25 4� 48 55
�,000 30 47 57 65
2,000 30 52 68 79
5,000 30 59 82 100
�0,000 30 6� 89 ��0
20,000 30 6� 9� 120
30,000 30 6� 92 �2�
Thetableshowsthatincreasingtheroofareaconnectedtothetanksignificantlyincreases
theamountofwateravailable,particularlyforlargertanks.However,increasingthetank
sizemorethan�,000litresfor50sqmofroofwillnotyieldanymorewater.Alargertank
connectedtojustonedownpipewouldbeineffective.Forroofareasof�00to200sqm,
installingatankgreaterthan5,000litreswouldhavelimitedbenefits.
Forexample,atankof5,000litresfor200sqmprovides�00klperyear.Doublingthe
tanksizeonlyincreasesthisto��0klperyear.
Step2.UsingTable�workouttheexpectedannualaveragewaterconsumptionforyour
householdforthepurposesof‘gardenwatering’,‘toiletflushing’and‘laundry’.
[Toiletflushingandlaundryarethesimplestinternalusestoconnecttoatank.]The
expectedconsumptionfortheseusesis244klperyear.
Step3.Comparetheexpectedannualconsumptionof244klagainsttheexpectedavailability
figuresinTable2.Thendecidehowmuchrainwateryouwanttocollecteachyear.
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Forexample,fromthefiguresinTable2,itcanbeseenthat:
• A�,000litretankconnectedtoonedownpipewillprovide30klperyear;• A5,000litretankconnectedtotwodownpipeswillprovide59klperyear;• A5,000litretankconnectedtothreedownpipeswillprovide82klperyear;• A5,000litretankconnectedtofourdownpipeswillprovide�00klperyear;• A20,000litretankconnectedtofourdownpipeswillprovide�20klperyear.
Rememberthatissuesofcost,space,appearanceandregulationsalsoneedconsiderationbeforeyouselectyourtanksize.
Thecalculationsshowthatthemostyoucancapturefroma200sqmroofisabout50%ofyourexpectedannualconsumptionfortheselecteduses.Anevenlargertank(say50,000litres,oreven�00,000litres)willnotcollectmuchmorewater.
Example 2
“Myroofareais�50sqm.IwanttoknowwhatsizetankIcouldinstallforarangeofuses.”
Step�.UsingCharts�to5,theaveragewateravailablefroma�50sqmroofcanbedeterminedfordifferenttanksizesandpurposes.(SeeExample�forinstructions).Recordthesenumbersinatable.(SeeTable3below).
Table 3. Summary of water available from a 150 sq m roof for a combination of uses.
Wateravailablefromtank(klperyear)
Tanksize
(litres)
Toiletflushing
fromChart�
Toilet&laundry
fromChart2
Gardenwatering
fromChart3
Garden&toiletflushing
fromChart4
Garden,toiletflushing&laundry
fromChart5
500 29 36 32 45 49
�,000 37 45 40 52 58
2,000 45 57 48 63 68
5,000 53 70 60 78 82
�0,000 58 79 70 87 88
20,000 85 78 90 90
30,000 88 85 9� 90
Thetableshowsmorewaterwillbeavailablegenerallyifthetankwaterisusedregularlyforarangeofpurposes.Thelargertanksarenotasefficientastheyarealreadycapturingmostofthewaterthatcanbecollectedfromaroofof�50sqm.Step2.UsingTable�,workouttheaveragewaterconsumptionfordifferentpurposes.Recordthesenumbersinatable.(SeeTable4nextpage).
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Table 4. Expected demand
Expecteddemand(fromTable�)inklperyear
Toiletflushing Toilet&laundry
Gardenwatering
Garden&toilet Garden,toilet&laundry
60 (60+43)�03
�4� (�4�+60)20�
(�4�+60+43)244
Step3.ComparetheexpectedannualconsumptionsinTable4withtheusablewaterinTable3.Noneofthetanksizeswillsatisfyalltheanticipateddemandfroma�50sqmroof,butwillstillmakeareasonablecombination.Alargerroofareawillprovidemorerainwater,however,issuesofcostsavings,installationcosts,space,appearanceandregulationswillhavetobeconsideredbeforeyoumakeafinaldecisiononwhichistheoptimumtanksize.
Contributing roof area (sq m)
Tank usage: toilet flushing
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Contributing roof area (sq m)
Contributing roof area (sq m)
Tank usage: toilet flushing and laundering
Tank usage: garden watering
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Contributing roof area (sq m)
Contributing roof area (sq m)
Tank usage: garden watering, toilet flushing and laundering
Tank usage: garden watering and toilet flushing