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Document ID ca-gcdwqgtdn-2016-12-29 Title Guidelines for Canadian Drinking Water Quality: Guideline Technical Document: N-Nitrosodimethylamine (NDMA) URL https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidelines-canadian-drinking-water-quality-guideline-technical-document-n-nitrosodimethylamine-ndma/page-2-guidelines-canadian-drinking-water-quality-guideline-technical-document-n-nitrosodimethylamine-ndma.html Jurisdiction /ca Subdomain(s) Drinking water, Water treatment, Monitoring and analysis Language en Status completed Analyzed at 2026-03-18 15:20:41.782067+00:00 Relevance Sets MAC for NDMA and provides treatment and monitoring guidance for operators.
10 Qualitative 7 Quantitative 0 Definitions

Q Qualitative Requirements (10)

Req ID Category Intent Legal Status Name Subdomain(s) Context Conditions Confidence
#Q001operationaltreatmentmandatoryDisinfection Strategy Modificationdrinking waterAny modification to the disinfection strategy needs to consider the potential formation of other disinfection by-products in a holistic manner and include pilot testing.When modifying the disinfection strategy to minimize NDMA formationhigh
#Q002administrativeoperationalrecommendedImplementation Guidance Consultationdrinking waterNote: Specific guidance related to the implementation of drinking water guidelines should be obtained from the appropriate drinking water authority in the affected jurisdiction.high
#Q003operationaltreatmentrecommendedNDMA Concentration Minimizationdrinking waterDrinking water operators should strive to keep NDMA concentrations low by implementing strategies to prevent its formation during treatment without compromising the effectiveness of disinfection.high
#Q004corrective_actionoperationalrecommendedShort-Term Exceedance Planningdrinking waterFor drinking water supplies that occasionally experience short-term exceedances above the MAC, it is suggested that a plan be developed and implemented to address these situations.When drinking water supplies occasionally experience short-term exceedances above the MAChigh
#Q005corrective_actionhealthrecommendedLong-Term Exceedance Alternative Sourcesdrinking waterFor more significant long-term exceedances that cannot be addressed through treatment, it is suggested that alternative sources of drinking water be considered.For significant long-term exceedances that cannot be addressed through treatmenthigh
#Q006monitoringoperationalrecommendedGeneral NDMA Monitoring Frequencydrinking waterIn general, monitoring of NDMA should be conducted on an annual basis.General requirementhigh
#Q007monitoringoperationalrecommendedQuarterly NDMA Monitoringdrinking waterWhere the characteristics of raw water or the treatment and disinfection strategies create the potential to produce NDMA, quarterly monitoring of treated water from surface and groundwater sources is recommended.Where raw water characteristics or treatment/disinfection strategies create the potential to produce NDMAhigh
#Q008monitoringoperationalguidanceReduced NDMA Monitoring Frequencydrinking waterThis may be reduced to an annual frequency if drinking water monitoring consistently does not show the presence of NDMA in the finished water.If drinking water monitoring consistently does not show the presence of NDMA in finished waterhigh
#Q009monitoringoperationalrecommendedNDMA Monitoring Locationsdrinking waterMonitoring should be conducted at the treatment plant and at the points of the distribution system with the longest disinfectant retention time.high
#Q010monitoringoperationalguidanceIncreased Frequency Episodic Monitoringdrinking waterIncreased frequency of monitoring may be required for facilities using surface water sources during periods when water characteristics are more favourable to the formation of by-products, which will vary according to the specific system.For facilities using surface water sources during periods when water characteristics are favourable to by-product formationhigh

P Quantitative Requirements (7)

Req ID Category Intent Legal Status Name Subdomain(s) Limit Type Limit Value Context Conditions Confidence
#P001chemicalhealthguidelineN-nitrosodimethylamine (NDMA)drinking waterMAC0.000 04 mg/LThe maximum acceptable concentration (MAC) for N-nitrosodimethylamine (NDMA) in drinking water is 0.000 04 mg/L (0.04 µg/L).high
#P002chemicalhealthguidelineN-nitrosodimethylamine (NDMA)drinking waterMAC0.04 µg/LThe maximum acceptable concentration (MAC) for N-nitrosodimethylamine (NDMA) in drinking water is 0.000 04 mg/L (0.04 µg/L).high
#P003designhealthguidelineStandard Lifetime Exposuredrinking waterrequirement70 yearsThe guideline for a carcinogen is normally established at a level at which the increased cancer risk is considered to be "essentially negligible" for a person exposed to that level in drinking water over a lifetime (70 years).Used for establishing carcinogenic guidelineshigh
#P004unknownhealthguidelineEssentially Negligible Cancer Risk Rangedrinking waterrequirement10-5 to 10-6 excess cancer riskHealth Canada has defined this term as a range from one new cancer above background per 100 000 people to one new cancer above background per 1 million people (i.e., 10-5 to 10-6) exposed to a contaminant at the MAC over a lifetime.Applies to lifetime exposure at the MAChigh
#P005unknownhealthguidelineNDMA MAC Excess Cancer Riskdrinking waterMAC10-5 excess cancer riskIn the case of NDMA, the MAC is established at a concentration that would present an "essentially negligible" risk of one new cancer above background per 100 000 people (i.e., 10-5) exposed to NDMA at the MAC over a lifetimeRisk at the MAC concentrationhigh
#P006operationalreportingrecommendedGeneral Monitoring Frequencydrinking waterrequirement1 per yearIn general, monitoring of NDMA should be conducted on an annual basis.General monitoring recommendationhigh
#P007operationalreportingrecommendedRisk-based Monitoring Frequencydrinking waterrequirement4 per yearWhere the characteristics of raw water or the treatment and disinfection strategies create the potential to produce NDMA, quarterly monitoring of treated water from surface and groundwater sources is recommended.When raw water or treatment/disinfection creates potential to produce NDMAhigh

D Definitions (0)

No definitions.