Well water testing in the Waterloo Region townships

Bacteria testing is free, funded by Public Health Ontario; nitrate or fluoride tests cost $21.40 each. In the townships, bottles are picked up and samples dropped off at the North Dumfries, Wellesley, Wilmot and Woolwich township offices (rural drop-off is on Tuesdays); the Woolwich Community Health Centre takes bacteria samples, and Region of Waterloo Library branches hand out bottles only. The urban receptions at 150 Main Street, Cambridge and 99 Regina Street South, Waterloo take samples Monday to Thursday.

The Region advises testing for bacteria three times a year (spring, summer and fall) and for nitrate and fluoride once a year, and offers well-water reminder emails.

Public Health Ontario's lab tests only for indicator bacteria: total coliforms and E. coli. Samples have to reach the lab within a day or two, so collect them early in the week and check the drop-off cut-off times. Nitrate and fluoride: $21.40 each through the Region. Other chemistry goes to a private lab.

Ontario's guide to testing and treating private wells reads the counts (per 100 mL) like this:

• E. coli above 0: unsafe to drink, with evidence of animal or human waste getting into the well. Stop drinking the water and call the health unit right away.
• Total coliforms above 5, no E. coli: significant evidence of bacterial contamination, usually surface water getting in. The water may be unsafe to drink: call the health unit, inspect and repair the well, shock-chlorinate it if needed and retest.
• Total coliforms of 5 or fewer, no E. coli: some evidence of bacteria, which may not be significant at these low levels. Keep testing to track the pattern.

Boiling water at a rolling boil for at least one minute kills harmful organisms but doesn't remove dissolved contaminants. To disinfect, the province says to shock-chlorinate the well and the entire household plumbing system. Between tests, check that the well cap and the sealant around the casing aren't cracked or damaged, and keep the ground sloping away from the well: Ontario's Wells Regulation requires owners to maintain a well so surface water can't get in.

Ontario's auditor general estimated in 2025 that about 1.3 million Ontarians rely on private wells, and that fewer than a third of well owners had tested in the previous 12 months (as reported by CBC). Well water can change with the seasons, after heavy rain or snowmelt, and after work on the well, which is why the health units ask for several tests a year.

Free bacterial water testing for all Huron and Perth county residents on a private well. Bottles are available from Huron Perth Public Health, hospital and municipal locations or your municipal office, and samples can be dropped off in Clinton, Exeter, Listowel, Milverton, Seaforth, Stratford and Wingham. Test at least three times a year, preferably in spring, summer and fall. Test for arsenic, fluoride, lead, nitrate and nitrite, sodium and uranium at least once every four to five years, at a licensed private lab for a fee.

• Bacteria (total coliforms and E. coli), several times a year and after flooding, heavy rain or work on the well.
• Nitrate, especially near farmland or septic systems: the province flags nitrate above 10 ppm as a health risk for infants, and reverse osmosis or distillation treats it.
• Naturally occurring minerals such as arsenic, uranium and radium, which the province lists as long-term health risks; a private accredited lab tests for them.

Read more: The well water guide.