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Document ID ca-gcdwqgtd-2014-02-05-10 Title Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Turbidity URL https://www.canada.ca/en/health-canada/services/publications/healthy-living/guidelines-canadian-drinking-water-quality-turbidity/page-11-guidelines-canadian-drinking-water-quality-turbidity.html Jurisdiction /ca Subdomain(s) Drinking water, Water treatment Language en Status completed Analyzed at 2026-03-17 14:55:45.550559+00:00 Relevance Defines health-based treatment limits and turbidity standards for filtration.

Q Qualitative Requirements (12)

Req ID Category Intent Legal Status Name Subdomain(s) Context Conditions Confidence
#Q001treatmenttreatmentrecommendedTurbidity Reduction (ALARA)drinking waterAlthough turbidity levels should be kept as low as reasonably achievable, treatment limitations are a key consideration in establishing guideline values for turbidity.high
#Q002operationaloperationalmandatoryTurbidity Data Analysisdrinking waterAnalysis needs to be conducted to determine whether further actions are needed to improve filter effluent turbidity.When assessing whether a system's performance satisfies the HBTL in at least 95% or 99% of turbidity measurementshigh
#Q003corrective_actionoperationalrecommendedInvestigation of Filter Performance Exceedancesdrinking waterNever to exceed values are also specified for each treatment process, because readings above this value suggest a significant problem with filter performance, and should be investigated and addressed immediately.If readings are above the never to exceed valuehigh
#Q004operationaloperationalguidanceGroundwater System Best Practicesdrinking waterBest practice for these systems includes appropriate well siting, construction and maintenance, as well as monitoring source water turbidity and ensuring that turbidity levels do not interfere with the disinfection and distribution of the water supply.For systems using a groundwater sourcehigh
#Q005monitoringoperationalrecommendedDistribution System Monitoringdrinking waterAll drinking water systems should monitor and control turbidity throughout the entire distribution system including areas with long retention times, decreased disinfectant residual, or that have demonstrated deteriorating water quality.high
#Q006corrective_actionoperationalrecommendedResponse to Unexpected Turbidity Increasesdrinking waterIf an unusual, rapid, or unexpected increase in turbidity levels does occur, the system should be inspected, the cause determined and appropriate corrective actions taken.If an unusual, rapid, or unexpected increase in turbidity levels does occurhigh
#Q007administrativeunknownmandatoryResearch Monitoring by Health Canadadrinking waterHealth Canada will continue to monitor new research in this area and recommend any changes to the guideline technical document that it deems necessary.high
#Q008operationaltreatmentrecommendedSurface Water and GUDI Turbidity Targetdrinking waterSystems whose source is either surface water or groundwater under the direct influence of surface water (GUDI) should strive to achieve a treated water turbidity target from individual filters or units of less than 0.1 NTU at all times.Systems whose source is surface water or GUDIhigh
#Q009operationaloperationalrecommendedGroundwater Turbidity Targetdrinking waterFor systems using a groundwater source, turbidity should generally be below 1.0 NTU.Systems using a groundwater sourcehigh
#Q010operationaloperationalguidanceDistribution System Entry Turbidity Best Practicedrinking waterTherefore, it is considered best practice for turbidity to be below 1.0 NTU in water entering the distribution system.Water entering the distribution systemhigh
#Q011treatmenttreatmentrecommendedTechnology-Specific Turbidity Performance Targetsdrinking waterWhere this is not achievable, the treated water turbidity levels from individual filters or units should be less than or equal to 0.3 NTU for conventional and direct filtration; less than or equal to 1.0 NTU for slow sand or diatomaceous earth filtration; and less than or equal to 0.1 NTU for filtration systems that use membrane filtration.Where a treated water turbidity target of less than 0.1 NTU is not achievable for SW or GUDI systemshigh
#Q012administrativeoperationalguidanceAcceptance of Higher Groundwater Turbiditydrinking waterIn some cases, a less stringent value for turbidity may be acceptable if it is demonstrated that the system has a history of acceptable microbiological quality and that a higher turbidity value will not compromise disinfection.For systems using a groundwater source where a history of acceptable microbiological quality is demonstratedhigh

P Quantitative Requirements (7)

Req ID Category Intent Legal Status Name Subdomain(s) Limit Type Limit Value Context Conditions Confidence
#P001physicaltreatmentrecommendedTreated Water Turbidity Target (Surface or GUDI)drinking watertreatment_goal< 0.1 NTUSystems whose source is either surface water or groundwater under the direct influence of surface water (GUDI) should strive to achieve a treated water turbidity target from individual filters or units of less than 0.1 NTU at all times.Applies to drinking water produced by systems that use conventional, direct, slow sand, diatomaceous earth or membrane filtration technologies.high
#P002physicaltreatmentrecommendedTreated Water Turbidity (Conventional and Direct Filtration)drinking watertreatment_goal<= 0.3 NTUWhere the 0.1 NTU target is not achievable, the treated water turbidity levels from individual filters or units should be less than or equal to 0.3 NTU for conventional and direct filtration.Conventional and direct filtration systems.high
#P003physicaltreatmentrecommendedTreated Water Turbidity (Slow Sand or Diatomaceous Earth Filtration)drinking watertreatment_goal<= 1.0 NTUWhere the 0.1 NTU target is not achievable, the treated water turbidity levels from individual filters or units should be less than or equal to 1.0 NTU for slow sand or diatomaceous earth filtration.Slow sand or diatomaceous earth filtration systems.high
#P004physicaltreatmentrecommendedTreated Water Turbidity (Membrane Filtration)drinking watertreatment_goal<= 0.1 NTUWhere the 0.1 NTU target is not achievable, the treated water turbidity levels from individual filters or units should be less than or equal to 0.1 NTU for filtration systems that use membrane filtration.Membrane filtration systems.high
#P005physicaltreatmentrecommendedTurbidity (Groundwater Source)drinking waterOG< 1.0 NTUFor systems using a groundwater source, turbidity should generally be below 1.0 NTU.Groundwater sources.high
#P006physicaloperationalguidanceTurbidity (Entering Distribution System)drinking waterOG< 1.0 NTUIt is considered best practice for turbidity to be below 1.0 NTU in water entering the distribution system.Water immediately prior to where disinfection is applied or entering the distribution system.high
#P007operationaltreatmentrecommendedHBTL Compliance Frequencydrinking waterrequirement>= 95 or 99 %Assessing whether a system's performance satisfies the HBTL in at least 95% or 99% of turbidity measurements requires the collection of data over a period of time.Applied to turbidity measurements over a period of time for individual filters or units.high

D Definitions (0)

No definitions.