wcc policy paper water chlorination

7/30/2019 WCC Policy Paper Water Chlorination

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Drinking WaterChlorination


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2 DrinkingWaterChlorinationWorldChlorineCouncilpositionpaper2008

Chlorinescriticalroleinprovidingsafedrinkingwateraround

Potentialhealthandenvironmentaleffectsofchlorineand

Considerationsforselectingdisinfectionmethods.

TheWorldChlorineCouncil(WCC)isaglobalnetworkrepresentingthechlorineandchlorinatedproducts

industries.Formedin1993,the WCCcurrentlyrepresentsover23national/regionalassociationsinover

27countriesaccountingforover80percentofglobalchlorineproduction.The WCCworksto improve

awarenessofthebenetsofchlorinechemistry;furtherthepracticeandunderstandingofresponsible

stewardship;andanticipateandrespondtorelevanthealth,environmentalandpublicpolicyissues.


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DrinkingWaterChlorinationWorldChlorineCouncilpositionpaper2008 3

Helping to provide sae drinking water around the globe

Chlorine is effective, affordable, and widely available for disinfection

Chlorineis usedtodestroydisease-causingorganisms inwater,anessentialstepindeliveringsafe

drinkingwaterandprotectingpublichealth.Chlorineisbyfarthemostcommonlyuseddisinfectant

inallregionsoftheworld.Wherewidelyadopted,chlorinehashelpedtovirtuallyeliminatewater-

bornediseasessuchascholera,typhoidanddysentery.Chlorinealsoeliminatesslimebacteria,molds

andalgaethatcommonlygrowinwatersupplyreservoirs,onthewallsofwatermainsandinstorage

tanks.Onlychlorine-baseddisinfectantsleave a benecialresiduallevel that remainsin treated

water,helpingtoprotectitduringdistributionandstorage.

Chlorineisaversatileandlow-costdisinfectantappropriateforanysizewatersystem,whetherit

servesaremoteruralvillageora largemoderncity.Wherepipedwatersuppliesarenotavailable,chlorinecanalsobe usedfortreating water inindividualhouseholds. Specially-packaged chlorine

bleachcandisinfecthouseholdwaterforlessthanUS$4/yearperfamily.

In addition, chlorine is critically needed for emergency relief efforts. In responding to the 2004

tsunamidisasterinSouthAsia,theWorldHealthOrganization(WHO)reported,

Water and sanitation: A global health crisis

Morethanonebillionpeopledonothaveaccesstoasafewatersupplywithin1kmoftheirhomes,

relyinginsteadonunprotectedlakes,streamsorshallowwellstomeethouseholdneeds.Evenwhere

relativelycleanwaterisavailableat acommunitysource,itcaneasilybe contaminatedas itiscol-

lected,carriedandstoredinthehome.WHOestimatesthatmorethan4,000peopledieeachday

fromdiarrhoealdiseasesresultingfromunsafewaterandlackofsanitation.Ninetypercentarechil-

drenundertheageofvewholiveindevelopingcountries.

Safe water: Essential for sustainable development

TheUnitedNationshasrecognizedthecriticallinkbetweensafewaterandsustainabledevelopment.

Accesstosafewaternotonlyreducesdisease,butalsoprovidesarangeofeconomicbenetsforacommunity.

Atthe2002WorldSummitonSustainableDevelopment,theUnitedNationsreafrmeditscommit-

menttoreducebyone-halftheproportionofpeoplewithoutaccesstosafewaterby2015.Meeting

thisgoalwillrequiresustained,coordinatedactionandenormousinvestmentseachyear.WHOhas

concludedthatglobalinvestmentstoimproveaccesstosafewateraccesswillyielddirectandindirect

benetsthatfarexceedtheassociatedcosts.


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Chlorine and disinection byproducts in drinking water do notpose signifcant health or environmental risks

Chlorine in drinking water is safe for consumption

Thesmallamountofchlorinetypicallyusedtodisinfectwaterdoesnotposeriskstohumanhealth.The

WorldHealthOrganization(WHO)hasestablishedaguidelinevalueof5mg/Lforchlorineindrinking

water,meaningthatsuchconcentrationsareconsideredacceptableforlifelonghumanconsumption.

Furthermore,WHOconcludesthatthisvalueisconservative,asnoadverseeffectsfromchlorinein

drinkingwaterwereobservedinstudiesreviewedbyWHO.

DBPs should be controlled, but disinfection must never be compromised

Anothersafetyconsiderationfortreateddrinkingwaterisdisinfectionbyproducts(DBPs),chemical

compoundsformedunintentionallywhenchlorineandotherdisinfectantsreactwithcertainorgan-

icmatterin water.Alldisinfectants formDBPs,althoughmuchmoreisknownaboutchlorination

byproducts than isknownaboutthebyproductsof otherdisinfectants.Forexample, toxicologicalstudiessuggestthatsometrihalomethanes(THMs)arecarcinogenictolaboratoryanimals,butonly

atlevelsmanythousandsoftimesgreaterthanthosefoundindrinkingwater.Researchhasshown

thatchloroform(themaintypeofTHM)isunlikelytocausecanceratextremelylowlevelsfoundin

drinkingwater.WhilethepotentialhealthrisksfromDBPsaresmallanduncertain,highlevelsofthese

chemicalsarecertainlyundesirable.WHOhasestablishedguidelinevaluesforseveralDBPs,including

trihalomethanes.

Guideline values or chlorine and trihalomethanes

Chlorine below5milligramsperliter(mg/L)*

Bromodichloromethane below0.06mg/L

Bromoform below0.10mg/L

Chloroform below0.20mg/L

Dibromochloromethane below0.10mg/L

* Foreffectivedisinfection,thereshouldbearesidualconcentrationoffreechlorineof0.5mg/L

afteratleast30mincontacttimeatpH


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DBPformationcanbereducedthroughcost-effectivemethods,particularlybyreducingtheamount

ofnaturalorganicmaterialinwater(throughltrationorothermeans)priortodisinfection.WCCsup-

portsadoptionofthesemethodswheneverpossible.However,asWHOstronglycautions:

AstarkexampleoftheimportanceofwaterdisinfectionisthecholeraepidemicthatbeganinPeruin

1991,andspreadto19LatinAmericancountries.Inadequatedisinfectionofmunicipalwatersupplies

wasamajorfactorcontributingtothespreadoftheepidemicthatcausedmorethanonemillionill-

nessesand12,000deaths.Duringtheoutbreak,ofcialswiththePanAmericanHealthOrganization

reportedthatconcernsaboutpotentialhealthrisksfromdisinfectionbyproductsledmunicipalities

andcommunitiesintheregiontoabandonchlorination.Oneofciallaterwrote,Ratherthanbeing

abatedby increaseuseofchlorination,thewaterbornetransmissionofcholerawas actuallyaided

becauseofworriesaboutchlorinationbyproducts.

Chlorination does not harm aquatic environments

Chlorinateddrinking water is unlikely tobe harmfulwhen discharged into aquaticenvironments.

AnextensiveriskassessmentconductedunderEuropeanUnionguidelinesexaminedpotentialharm

fromvariousprocessestomakedrinkingwaterusingsodiumhypochlorite.Thisassessmentfoundno

signicantenvironmentalrisksfromchlorineorbyproductsformedduringdrinkingwaterchlorina-

tion.TheDBPsformedindrinkingwaterdependonthenatureandquantityoforganicmatterpresent

aswellasonthedisinfectantandothertreatmentsused.Indrinkingwatertheprincipalbyproducts

aretrihalomethanes(THMs;mainlychloroform)andhaloaceticacids(HAAs),withsmalleramounts

ofotherbyproducts.Directwholeefuentexperimentsrepresentingvarioususes,includingdrink-

ingwater, have shown that nosignicant amounts ofpersistentand potentially bioaccumulative

substancesareformed.ToxicitytestsonthesemixturesdemonstratedthatthepresenceofDBPsdid

notincreasethetoxicity.

Amajorconcernfromthepastwastheformationofsomehighly-chlorinated,high-hazardmolecules,

such asdioxins,resultingfromchlorineused inpaperpulpbleaching.However,dioxinswereonly

formedfromactivechlorineunderspecicconditions:acidpHandinthepresenceofcertainphe-

nolssuchasthoseabundantinthelignincomponentofwood.Thereisnosignicantformationof

dioxinsorotherhigh-hazardmoleculesatneutraloralkalinepH.Allcurrentusesofactivechlorine

formicrobialcontrolandcleaningtakeplaceatalkalineorneutralpH.


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Disinection technologies must be eective, aordableand appropriate or local conditions

Various technologies are available

Chlorinationisthemostwidelyuseddisinfectant,bothincentralizedwaterdistributionsystemsand

forpoint-of usetreatment in individual households. Its effectivenessagainsta widespectrum of

disease-causingorganisms,relativelylowcostandhighreliabilitycontributetoitspopularity.

Chlorineisappliedtowatereitheraselementalchlorine(chlorinegas),orthroughtheuseofchlorin-

atingchemicalssuchascalciumhypochlorite(tabletsorgranules)orsolutionsofsodiumhypochlorite

(liquidbleach). While varying informandconcentration, eachproducesfreechlorine toattack

germsinwater.Theleveloffreechlorinecanbeeasilymonitored,providinganimportantmeasureof

waterquality.Aresiduallevelofchlorinehelpsprotecttreatedwatertreatedwaterinthedistribu-

tionsystem,particularlyimportantforolderwatersystems.

Anumberofalternativemethodsareavailablefordrinkingwaterdisinfection.Theseinclude:ozone,

apowerfuldisinfectingagentgeneratedbypassingoxygenordryairthroughasystemofhighvolt-

ageelectrodes;chlorinedioxide,apowerfulchemicalthatcontainschlorinemolecules,butdisinfects

through a differentmechanism than freechlorine; andultraviolet (UV) radiation, a non-chemical

methodtodisinfectwaterusinglightgeneratedbyspeciallamps.Inaddition,someharmfulmicro-

organismscanberemovedfromwaterthoughltrationorotherphysicalmeans.Filtrationmethods

rangefromsimplesandltersforhouseholdtreatment,toreverseosmosissystemsinstate-of-the-art

treatmentplants.

Eachdisinfectiontechnologyhasuniquestrengthsandlimitations.Nosingledisinfectionmethodis

rightforallcircumstances,andinfact,amulti-stepprocessmaybeappropriatetomeetoveralltreat-

mentgoals.


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Considerations for selecting disinfection methods

Efcacy against pathogensControllingmicrobialcontaminationmustalways

begivenprimaryimportance.Whilechlorineiseffectiveagainstmostpathogens,

additional treatmentsteps maybe needed where resistantorganisms such as

or areaconcern.

Laws and regulationsTreatmentprocessesandnaldrinkingwaterqualitymust

meetlocalstandards.

Source water qualityThecharacteristicsoflocalsourcewater,suchasturbidity

andorganicload,willimpactdisinfectionrequirements.

Residual protectionOnlychlorine-basedproductsprovidearesiduallevelof

disinfectantthatremainsinwatertopreventmicrobialre-growthandhelppro-

tecttreatedwaterduringdistributionandstorage.Therefore,nootherdisinfec-

tionmethodbyitselfcanprotectwaterallthewaytothetap.

Local capacitySufcientresources,suppliesandtrainingmustbeavailableto

maintainserviceaftertreatmenttechnologiesareadopted.

SaetyAlldisinfectionchemicalsrequireproperstorageandhandlingpractices.

Safetyguidelinesareavailablefromnationalandregionalchlorineassociations.

Consumer expectationsEducationaleffortsmayhelplocalcommunitiesunder-stand the need for water disinfection, and ensure acceptance of treatment

methods.

AordabilityWaterserviceand/orhometreatmentproductsmustbeaffordable

toconsumers.


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[email protected]

WCCmembers

Producer Associations

AsociacionNacionaldelaIndustriaQuimica(Mexico)

www.aniq.org.mx/

CanadianChlorineChemistryCouncil

www.cfour.org

ChlorineChemistryDivisionoftheAmericanChemistry

Council

www.americanchemistry.com/chlorine

ChlorineInstitute

www.cl2.com

Clorosur

www.clorosur.org

EuroChlor

www.eurochlor.org

IndianChemicalManufacturersAssociation

JapanSodaIndustryAssociation

www.jsia.gr.jp

KoreaChlor-AlkaliAssociation

PlasticsandChemicalsIndustriesAssociationofAustralia

www.pacia.org.au

Taiwan(China)Acid&AlkaliIndustryAssociation

Product Sector Associations

Asia-PacicVinylNetwork

EuropeanCouncilofVinylManufacturers

www.ecvm.orgHalogenatedSolventsIndustryAlliance

www.hsia.org

VinylCouncilofAustralia

www.vinyl.org.au

VinylCouncilofCanada

www.plastics.ca/vinyl

VinylEnvironmentalCouncil(Japan)

www.vec.gr.jp

VinylInstitute

www.vinylinfo.org

Corresponding Associations

RusChlor,theRussianchlor-alkaliassociation

ChinaChlor-AlkaliIndustryAssociation[pending]

wcc policy paper water chlorination

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