Well water testing in Canada: what to test, how often and where

Most of Well & Field is written for the United States. The chemistry of a well doesn’t change at the border, but the rules of thumb do: Canada has its own guideline values, tests on a different schedule and, in some provinces, pays for the test. This guide collects the Canadian numbers in one place.

One thing is the same in both countries. Nobody tests a private well for you. Health Canada says a private well owner is responsible for monitoring and maintaining the quality of the water¹.

How often to test

Test	How often	Acceptable level
E. coli	Every 6 months, or more often	None in a 100 mL sample
Total coliforms	Every 6 months, or more often	None in a 100 mL sample
General water quality: pH, iron, chloride, alkalinity, hardness, total dissolved solids and others	Every 2 years	See the guideline values below
Chemical contaminants	Varies by contaminant	Ask your local public health authority

Source: Health Canada, Test your well water.

That is twice as often for bacteria as the yearly test described in our US well water testing guide.

Test again, whatever the calendar says, after any of these¹:

• heavy rain or flooding, a long dry spell or drought, or a fire
• a long period when the well wasn’t used
• repairs to the well
• a change in the water’s colour, taste or smell
• a change in how nearby land is used

Health Canada also flags wells that are more vulnerable: dug wells, wells in bedrock or under only a thin layer of soil, and shallow wells with less than 25 metres of casing¹.

What the provinces say

Provinces and territories run drinking water programs, so the practical details depend on where you live. Three examples:

Province	How often	How it works
Ontario	Regularly, and after spring thaw, heavy rain, flooding or well work	Free testing for E. coli and coliforms through Public Health Ontario. Results online in 2 to 4 business days
Alberta	At least twice a year	Alberta Precision Laboratories tests private systems for total coliforms and E. coli
British Columbia	At least once a year, and at once if clarity, colour or taste changes	The owner arranges and pays for testing at a qualified laboratory

Sources: Public Health Ontario (June 2026), MyHealth Alberta (December 2024), HealthLinkBC File 05b (July 2025). Check your own province for current details.

Ontario’s free test covers bacteria only. For minerals and chemicals, Public Health Ontario says to contact a licensed laboratory³. British Columbia recommends chemical testing when a well is completed and annually after that, for nitrates, fluoride and metals such as arsenic, lead, copper and manganese⁵.

For any other province or territory, Health Canada’s advice is to ask the provincial or territorial drinking water authority or your local public health unit, which can also point you to an accredited laboratory¹.

Canadian guideline values

These are Health Canada’s Guidelines for Canadian Drinking Water Quality, from the summary tables published in December 2025². “MAC” is the maximum acceptable concentration, a health-based value. An aesthetic objective is about taste, staining or appearance.

Parameter	Health-based MAC	Aesthetic objective
E. coli	None detectable per 100 mL
Total coliforms	None detectable per 100 mL
Nitrate	45 mg/L (10 mg/L as nitrogen)
Nitrite	3 mg/L (1 mg/L as nitrogen)
Arsenic	0.010 mg/L
Lead	0.005 mg/L
Uranium	0.02 mg/L
Fluoride	1.5 mg/L
Manganese	0.12 mg/L	0.02 mg/L or less
Iron		0.1 mg/L or less
Sodium		200 mg/L or less
Total dissolved solids		500 mg/L or less

Source: Health Canada, Guidelines for Canadian Drinking Water Quality, Summary Tables (December 2025).

For arsenic and lead, Health Canada adds that levels should be kept as low as reasonably achievable².

Where Canada and the US differ

If you use American guides or an American test kit, these are the numbers to watch²⁶.

Parameter	Canada	United States
Arsenic	0.010 mg/L	0.010 mg/L
Nitrate, as nitrogen	10 mg/L	10 mg/L
Lead	0.005 mg/L	Action level 0.015 mg/L
Uranium	0.02 mg/L	0.030 mg/L
Fluoride	1.5 mg/L	4.0 mg/L

Sources: Health Canada Summary Tables (December 2025) and US EPA National Primary Drinking Water Regulations (August 2026).

Our result checker uses the US numbers. For a Canadian well, compare lead, uranium and fluoride with the table above instead.

If a result comes back high

Health Canada’s guidance by type of result¹:

• E. coli present: the water is not safe to drink. Boil water used for drinking, cooking and brushing teeth, or use another safe source, and retest promptly.
• Total coliforms present, no E. coli: you can keep using the water while you wait for further results. Retest, and if contamination is confirmed, shock disinfect the well and fix the cause.
• A chemical above its guideline: take more samples and plan corrective action.
• A general parameter above its objective: the water can generally still be drunk, but treatment may help with staining, scale, taste or smell.

The practical steps are the same on both sides of the border, and our US guides explain them in detail: coliform bacteria, shock chlorinating a well, nitrate and arsenic. Read them with the Canadian values from this page.