Q-2, r. 40 - Regulation respecting the quality of drinking water

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5.1. The filtration and disinfection treatment prescribed in the first paragraph of section 5 must, according to the average number of Escherichia coli bacteria per 100 mL of sampled raw water, ensure a proven rate of effectiveness in the elimination of pathogenic microorganisms present in raw water at least equal to the percentage indicated in the following table for each category of microorganisms:

Average number Category of Elimination
of Escherichia pathogenic percentage
coli bacteria microorganisms
(per 100 ml of
sampled raw water)

Virus 99.99%
≤15 Giardia cyst 99.9%
Cryptosporidium oocyst 99.9%

Virus 99.999%
>15 and ≤150 Giardia cyst 99.99%
Cryptosporidium oocyst 99.9%

Virus 99.9999%
>150 and ≤1,500 Giardia cyst 99.999%
Cryptosporidium oocyst 99.99%

Virus 99.99999%
>1,500 Giardia cyst 99.9999%
Cryptosporidium oocyst 99.999%

For the purposes of this section, the average number of Escherichia coli bacteria is established on the basis of the arithmetical average of the number of bacteria appearing in the analysis results over 12 consecutive months corresponding to the highest average observed within a reference period comprised of the last 36 months.
O.C. 70-2012, s. 7.