Technical Support Document for Ontario Drinking Water Standards, Objectives and Guidelines

2006·1.8 MB·English

by  Ontario Ministry of the Environment

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Technical Support Document for
Ontario Drinking Water Standards, Objectives and
Guidelines
June 2003
RevisedJune 2006
PIBS 4449e01
Protectingourenvironment.

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TechnicalSupportDocumentforOntarioDrini<ing-waterQualit> Standards,ObjectivesandGuidelines
TABLEOFCONTENTS
ONTARIO DRINKING-WATERQUALITY STANDARDS,OBJECTIVESAND
1
GUIDELINES
1
1.1 introduction 1
1.2 Typesofstandards, objectivesandguidelines 1
WATERQUALITYCHARACTERISTICS
2. 3
2.1 Microbiologicalcharacteristics 3
2.2 Chemical characteristics 4
2.3 Physical characteristics 4
2.4 Radioactivecharacteristics 5
2.5 Aesthetic characteristicsandotherconsiderations 5
WATERMONITORING
3. 6
3.1 Rawwatercharacterization 6
3.2 Rationale forwatermonitoring 6
TABLE -MICROBIOLOGICAL STANDARDS
1 8
TABLE2-CHEMICAL STANDARDS 8
TABLE 3-RADIONUCLIDE STANDARDS 1
TABLE4-OBJECTIVESANDGUIDELINES 12
APPENDIXA-DESCRIPTION OF INDIVIDUAL PARAMETERS 14
ANNEXA: CyanobacterialTo.xins- Microcystin-LR FlowChart 35
GLOSSARY
36

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Technical SupportDocumentforOntarioDrinking-waterQualityStandards,ObjectivesandGuidelines
ONTARIODRINKING-WATERQUALITYSTANDARDS,OBJECTIVESAND
1.
GUIDELINES
1.1 Introduction
Thepriman purposeoftheOntario Drinking Water Standards. ObjectivesandGuidelines isto
provide information fortheprotectionofpublic healththrough theprovision ofsafedrinking
water. Water intended forhumanconsumption shall notcontaindisease-causingorganismsor
unsafeconcentrationsoftoxic chemicalsorradioactive substances. Watershouldalso be
aestheticallyacceptableand palatable.Taste,odour, turbidit) andcolourareparametersthat,
whencontrolled, result in waterwhich isclear, colourlessand withoutobjectionableor
unpleasanttasteorodour. Otheraspectsofwaterqualit\ such ascorrosiveness, atendencyto
form incrustationsandexcessivesoapconsumption should becontrolledon thebasisof
economicconsiderationsbecauseoftheireffectson thedistribution system and/orthe intended
domesticand industrial useofthewater.
Parametersandtheirassociated standardsand objectivesare listedalphabetically inTables 1
through4. A briefdescription isprovided forthese parameters in AppendixA. Some
parameters, suchasalkalinit\, pH andtaste, whichdo nothave specific objectives, are listed
because forthem there isan idealcondition orrange forwatertreatment plantoperationor
aesthetic waterqualit\
Thisdocument is intended to providesupportingdocumentation fortheOntario Drinking-Water
Qualit) Standards Regulation O. Reg. 169/03 and serveasareference forthedesign and
operation ofwatertreatmentplantstoproducewaterthatcontinuousK satisfiesthe standards,
objectivesandguidelinesofdrinking-waterquality\Thisdocument alsomakesreferencetothe
Procedure forDisinfectionofDrinking WaterinOntario.
Thisdocument shouldalso serveasareference forprofessional engineerspreparingEngineers'
Evaluation Reportsas in accordancewith Schedule21 ofthe Drinking-Water Systems
Regulation. O. Reg. 170 03. made underthe Safe Drinking Water.Act, 2002 orforaMinistry
engineerin reviewing applications forapproval ofdrinking-waters>stems.
Incarryingouttheirresponsibilitiesrelatedtodrinkingwater, theowner/operatorofadrinking-
watersystem should considerthedrinking-waterquality standards,objectivesand guidelinesto
assessacceptabilityofthewater.
1.2 Typesofstandards,objectivesandguidelines
Standards,objectivesandguidelinesareconsideredtobetheminimum level ofdrinking-water
quality and innoway shouldberegardedas impKingthatallowingthedegradationofahigh
quality watersuppK tothe specified level orrange is acceptable. The standards, objectivesand
guidelinesdescribed herein havebeenderived fromthebest information currenth available.
Societ)-continuesto introducenew chemicals into theenvironmentthathaveapotential to
contaminatedrinkingwatersupplies. .Advances intechnolog\ ma\ identify new micro-
organismsthatarepathogenic orthataffectthequality ofdrinkingwater. Standards,objectives
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TechnicalSupportDocumentforOntarioDrini<ing-waterQualityStandards,ObjectivesandGuidelines
andguidelinesarereviewedasnewdata becomesavailable. Criteriaused toevaluatethesafety
ofdrinkingwaterarecontinually reassessedas new parametersare identifiedandhealtheffects
researchadvances. Drinking-waterqualitycriteriamustconsiderall factorsthataffectthe
qualityofwaterandthe public health significance.
Thisdocumentaddressesthe followingtypesofhealth-based standards:
Maximum AcceptableConcentration(MAC)
TheMAC isestablished forparameterswhich when presentaboveacertain
concentration, haveknownorsuspectedadversehealtheffects.The lengthoftimethe
MACcan beexceededwithouthealtheffectswill dependonthe natureand
concentration oftheparameter.
Interim Maximum AcceptableConcentration (IMAC)
The IMAC isestablished forparameterseitherwhenthereare insufficientto.xicological
datatoestablish aMAC with reasonablecertainty, orwhen it isnot feasible, for
MAC
practical reasons, toestablisha atthedesired level.
Ontario Regulation 169/03, OntarioDrinking-WaterQuality Standards, made underthe Safe
Drinking WaterAct,2002, prescribesMACsand IMACsasstandardsofOntariodrinking-water
quality.
Turbidity
Thesubstancesand particlesthatcauseturbiditycan beresponsible forsignificant
interferencewithdisinfection, can beasourceofdisease-causingorganismsand can
shieldpathogenicorganismsfromthedisinfection process.
Turbidity isan important indicatoroftreatmentefficiencyandtheefficiencyoffilters in
particular. A significantrelationship hasbeendemonstrated betweenturbidity increases
andthenumberofGiardiacystsand Cryptosporidium oocystsbreakingthrough filters.
PerformanceCriteriaforturbidityasan indicatoroftheefficiencyoffilters in relationto
creditsforGiardiacystsandCr>ptosporidiumoocystsremoval havebeen prescribed in
the"Procedure forDisinfectionofDrinking Water inOntario".
OntarioRegulation 170/03 prescribesturbidityasanadverseresult ifthedrinking-water
system isrequiredtoprovidefiltration,andaresult indicatesthatturbidityexceeds 1.0
NephelometricTurbidityUnits(NTU) in:
i. agrabsampleofwatertaken troma filtereffluent line: or,
ii. twosamplesofwaterfrom afiltereffluent linethataretestedbycontinuous
monitoringequipment, if
a. twosamplesweretaken 15 minutesormoreapartandthe laterofthetwo
sampleswasthefirstsamplethatwastaken 15 minutesormoreaftertheearlier
sample;and,