Sampling: How to sample your water for bacteria

The Timiskaming Health Unit recommends that well owners have their well water tested at least three times per year to determine if there are seasonal changes in the quality of the drinking water. Additional water samples should be taken if any changes in the drinking water are detected. This can include a change in taste, smell or colour.

If you feel you may have chemical problems with your water, you should submit a water sample to a private, accredited lab. Further information can be obtained from the Timiskaming Health Unit.

In Ontario, the public health labs test for the presence of indicator bacteria in drinking water (Total Coliform and E. coli).

Sampling your well water for accurate results:

1. A well owner can obtain sample bottles from the public health unit free of charge. These bottles are sterilized and sealed and are the only collection method accepted by the lab.
2. Plan to sample the well water on the same day that it is to be delivered to the health unit. A water sample should not be left sitting for long periods of time as this can lead to inaccurate results. The Timiskaming Health Unit accepts private well water samples see schedule here.
3. Remove the aerator or screen from the faucet.
4. Disinfect the faucet spout with alcohol or a dilute bleach solution (1 part household bleach to 10 parts water).
5. Run the cold water for 3 to 4 minutes before taking the sample. This will flush the plumbing system and provide fresh well water at the tap.
6. Wash and sanitize hands.
7. Remove the lid, being careful not to touch the inside of the lid or the bottle.
8. Fill the bottle to the fill line (200 mL) and close the lid tightly.
9. Once collected, the sample should be placed in a container with an ice pack and delivered to the health unit as soon as possible. (Do not freeze the water sample)
10. Ensure that the forms accompanying your sample are filled out correctly. It if the form is not complete or is inaccurate, the lab will not test your water sample. Be sure to include your name, phone number, address, the date the sample was collected, and other information requested on the form.
11. Once you receive your results, you should keep them in file and not throw them away. Having a drinking water quality history on your well is important and may be valuable information should you want to sell your house.

1. Do not take water samples from outside taps
2. Flaming the tap for disinfection is not recommended as this can damage the faucet.
3. Do not touch the inside of the bottle or its lid
4. Do not put the lid down. Always hold it in such as way that it will not become contaminated.
5. Do not rinse the bottle with water before filling it.
6. Do not use a bottle with a broken lid seal. It may be contaminated thereby affecting your results.
7. Do not forget to fill out the forms completely. The lab will not test a sample with incomplete forms.
8. Do not throw away your results. It is important information to keep for your records and may be referenced in the future.
9. Do not submit samples from high-risk water supplies, such as lakes, rivers or streams, unless water has been properly treated first.

Water Wells: Best management Practices. Revised Edition, 2003. Ontario Ministry of Agriculture, Food and Rural Affairs.
(Available free from the Timiskaming Health Unit).

Water sample bottles can be obtained from the Timiskaming Health Unit