Well Aware | How To Be



Click here to learn about testing for other parameters in your water


19 count of total coliform.
This water is unsafe to drink.

Coliform Count

What are Total Coliforms?

Coliforms are bacteria associated with environmental sources such as vegetation and soil or possibly from faecal material. Even a low count of total coliforms (1-5) may indicate the presence of other more harmful bacteria with similar life cycles. Caution and retesting is recommended. A higher total coliform count (6-80) is a strong indicator that disease causing micro-organisms may be present. Assume that your water is unsafe for drinking without treatment.

Very high count of e. coli.
This water is unsafe to drink.

Ecoli Sample

What is E. coli?

E. coli is a bacteria associated with human or animal faecal matter. Any detectable presence of E. coli in your well water means your water is unsafe for drinking without treatment.

These tests would be reported as safe to drink.

negative plate

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What Could be wrong with my water?

Even though your water may appear to be fine, there are many possible contaminants that that you can not taste, see or smell.

Drinking contaminated well water can make you and your family members ill. It can even be fatal.

Bacterial contamination may cause stomach cramps, diarrhoea, vomiting or other problems.

Chemical contamination is equally dangerous. The effects can vary.

Test your water for indicators of bacterial contamination.

It is recommended that you test your well water regularly for the indicator bacteria total coliforms and E. coli.

If present, it is an indication that the water may contain harmful micro-organisms that can make you sick.

Testing at least three times a year for bacteria is recommended by the Ontario Ministry of the Environment and the Ontario Ministry of Health and Long-Term Care.

Early spring is a good time to test your well water for bacteria. Another good time is the day after a heavy rainfall. Melting snow and running water can carry surface contaminants into your well water. If your well water is safe under these conditions, it is most likely to be safe the rest of the year.

Test your water even if your water seems fine, because you can not always taste, smell or see bacteria or other contaminants. Do not rely on your neighbour's test results - wells that are only a few steps apart may have different water quality.

Besides routine testing, you should also test:

Testing for bacteria

These tests are free. Contact your local health unit for more information.

A single test for total coliforms and E. coli is not always enough to determine the quality of your well water. If your well has not been tested regularly, submit three samples at least one to three weeks apart. Do not send several samples at the same time. If the well consistently shows acceptable total coliform and E. coli counts, sample at least three time each year.

How to sample for bacteria

The following rules apply to routine sampling for colifors and E. coli. For other tests, follow the sampling rules provided by the testing laboratory.

testing bottle

Content and photos for this page provided by Public Health Ontario.