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Document ID ca-gcdwqgtd-2014-02-05-7 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-8-guidelines-canadian-drinking-water-quality-turbidity.html Jurisdiction /ca Subdomain(s) Drinking water, Water treatment Language en Status completed Analyzed at 2026-03-17 14:49:22.723812+00:00 Relevance Technical guideline on turbidity limits and its impact on microbiological safety.

7 Qualitative 10 Quantitative 11 Definitions

Q Qualitative Requirements (7)

Req ID	Category	Intent	Legal Status	Name	Subdomain(s)	Context	Conditions	Confidence
#Q001	monitoring	operational	guidance	Interpretation of distribution system turbidity	drinking water	Turbidity measurements can be used as an indication of changes to distribution system conditions, but should not be automatically interpreted as an indication of an unsafe water supply.	When evaluating changes to distribution system conditions	high
#Q002	operational	operational	recommended	Turbidity measurement usage by operators	drinking water	Measurements should be used by operators as a useful tool for monitoring plant operations and distribution system conditions.		high
#Q003	operational	treatment	guideline	Groundwater system best practice	drinking water	However, for turbidity in drinking water systems supplied by groundwater it is best practice to generally be below 1.0 NTU.	Drinking water systems supplied by groundwater	high
#Q004	treatment	treatment	recommended	Filtration system optimization	drinking water	Filtration systems should be operated to reduce turbidity levels to the lowest levels possible.		high
#Q005	treatment	treatment	recommended	Treated water turbidity target	drinking water	Water suppliers should strive to achieve a treated water turbidity target of 0.1 NTU at all times.	At all times	high
#Q006	monitoring	health	recommended	Membrane integrity breach detection	drinking water	Since it is difficult to quantify the microbial risk associated with various levels of membrane integrity loss, utilities should focus on the immediate detection of any breach in membrane integrity as a way to minimize the potential for breakthrough of pathogenic organisms (U.S. EPA, 2001b).	Membrane filtration systems	high
#Q007	operational	operational	guidance	Supply chain turbidity minimization	drinking water	It is advised that water suppliers strive to achieve turbidity that is as low as possible at all points in the supply chain.	At all points in the supply chain	high

P Quantitative Requirements (10)

Req ID	Category	Intent	Legal Status	Name	Subdomain(s)	Limit Type	Limit Value	Context	Conditions	Confidence
#P001	physical	treatment	recommended	turbidity	drinking water	OG	< 1.0 NTU	For turbidity in drinking water systems supplied by groundwater it is best practice to generally be below 1.0 NTU.	Drinking water systems supplied by groundwater	high
#P002	physical	treatment	guideline	turbidity	drinking water	treatment_goal	0.3 NTU	Referred to as the Health-Based Treatment Limit (HBTL) of 0.3 NTU.	Treated water	high
#P003	physical	treatment	recommended	treated water turbidity	drinking water	treatment_goal	<= 0.1 NTU	Water suppliers should strive to achieve a treated water turbidity target of 0.1 NTU at all times.	Treated water	high
#P004	physical	operational	recommended	turbidity	drinking water	OG	<= 1.0 NTU	A turbidity value of 1.0 NTU for water entering the distribution system is recommended.	Water entering the distribution system	high
#P005	physical	treatment	guidance	LT2ESWTR Filter Effluent Turbidity Standard	drinking water	requirement	0.15 NTU	Additional credit for public supplies meeting a filter effluent turbidity standard of 0.15 NTU	Standard for receiving additional log removal credit	high
#P006	physical	treatment	guidance	LT2ESWTR Maximum Individual Filter Measurement	drinking water	requirement	0.3 NTU	No individual filter measurement greater than 0.3 NTU for LT2ESWTR credit	Maximum individual filter measurement	high
#P007	physical	treatment	guidance	PSW Excellence Filter Effluent Turbidity	drinking water	requirement	< 0.10 NTU	Criteria representing excellence in water treatment	In 95% of measurements	high
#P008	physical	treatment	guidance	PSW Excellence Maximum Filtered Water Turbidity	drinking water	requirement	0.30 NTU	Maximum filtered water turbidity for PSW excellence criteria	Maximum value	high
#P009	physical	treatment	recommended	Filtered Water Turbidity for Aluminum Control	drinking water	treatment_goal	< 0.15 NTU	When treatment is properly optimized, results in very low aluminum residual	Plants using aluminum salts	high
#P010	physical	aesthetic	guideline	Visual Detection Threshold	drinking water	AO	>= 5.0 NTU	Level at which there is increasing visual detection and consumers may find water unacceptable		high

D Definitions (11)

Req ID	Name	Context	Confidence
#D001	T99 value	contact time required for 99% inactivation	high
#D002	True colour	the colour of water from which turbidity has been removed	high
#D003	DBPs	disinfection by-products	high
#D004	THMs	trihalomethanes	high
#D005	HAAs	haloacetic acids	high
#D006	UV	ultraviolet	high
#D007	Microfiltration	pore size: 0.1-10 µm	high
#D008	Ultrafiltration	pore size: 0.01-0.1 µm	high
#D009	Nanofiltration membranes	0.5-2 nm	high
#D010	Bag and cartridge filters	pore size typically 0.2-10 µm	high
#D011	Reverse osmosis membranes	generally considered non-porous	high