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Well Water Safety

Bacteriological Testing

Your well water quality can change throughout the year depending on the condition of your well. That is why, it is very important to routinely test your water supply:

  1. At least 3 times a year, usually once every 3 to 4 months
  2. More frequently for high-risk well or if well has history of water quality problems

Once the Provincial Laboratory has received your water sample, they will test for the presence or absence of two specific groups of indicator organisms:

  • Total coliforms
  • E. coli (Escherichia coli)

The presence of these organisms acts as an early warning signal of health risks related to consuming your well water.

What are Total coliforms?

Total Coliforms
  • Generalized group of bacteria found throughout the environment including soils, vegetation, and in human and animal feces.
  • Their presence may indicate a problem with your water supply, possibly through surface water contamination.

What is E. coli?

E. Coli
  • A group of bacteria that live in the intestines of warm-blooded animals
  • Their presence indicates recent fecal contamination such as sewage, and that there is a problem with your water supply.

Interpreting your Results

You will receive your test results through the mail usually one week after the date of submission.

The following table provides a summary to help you interpret your results.

Total coliforms
(per 100mL of water)

E. coli
(per 100mL of water)




Considered a SAFE supply.

1 to 5


Evidence of Bacterial Contamination. Further assessment is required. Please contact the Environmental Help Line at 1-888-777-9613.

6 to >80 or EST. or O/G

1 to >80 or EST. or O/G

UNSAFE for drinking unless boiled or treated.

Contaminated well water poses a health risk to the public. Ingesting well water that is considered "UNSAFE" can cause a variety of health effects including symptoms of nausea, vomiting, and diarrhea through to long term disability and even death.