Why test your well water
Water quality can change over time. Test your well water frequently to remain up-to-date on the quality of your family's drinking water.
When to test your well water
Test for bacteria:
- frequently—at least three times a year (spring, summer and fall);
- after flooding, major rainfall or after snow has melted;
- after you have disinfected your well because of a positive test result (if your well is not properly sealed or the water supplying your well is contaminated, your water could become contaminated again);
- after well maintenance; and
- after nearby construction, including excavation or septic system installation.
Test for chemicals if:
- chemical contamination is suspected; or
- chemicals are known to occur naturally at elevated levels in the area groundwater.
How to test your well water for bacteria
- Get a well water sample bottle and submission form:
- Collect your drinking water sample and complete the submission form:
- Remove the strainer screen and disinfect the end of the household water tap (disinfect using an alcohol swab or solution of one part household bleach to 10 parts water).
- Run cold water through the tap for three to four minutes.
- Fill the sample bottle to the indicator line directly from the tap without rinsing the bottle or lid. Do not set the lid down or touch the inside/lip.
- Complete the submission form with the required information. Enter the Halton Region Health Unit number (2236) on the submission form.
- Drop off your sample at one of the local water depots within 24 hours of collecting the sample.
- The sample should be kept refrigerated if it is not dropped off immediately.
- A courier picks up samples from the local water depots and delivers them to the Public Health Ontario Laboratory. There is no charge for this service.
Hamilton Public Health Ontario Laboratory is located at 250 Fennell Avenue West, Hamilton, ON L8N 3R5
Tel: (905) 385-5379, Toll free: 1-866-282-7376
Please see the Public Health Ontario website (external link) for Hamilton laboratory location, contact information and hours of operation.
Water depot locations
On holidays, water depot hours may change.
Burlington
Conservation Halton Office
2596 Britannia Rd.
Hours: Tuesdays & Wednesdays
8:30 a.m. - 4 p.m.
Oakville
Halton Regional Centre
1151 Bronte Rd.
Hours: Mon. – Thurs.
8:00 a.m. – 5:00 p.m.
How to get your well water test results
There are several ways to get the results of your well water test from the Public Health Ontario Laboratory: by mail, telephone, in person and electronically.
Please visit Public Health Ontario Get Your Test Results (external link) webpage for more information.
Understanding your test results
Well water samples submitted to the Public Health Ontario Laboratory are tested for indicator bacteria (total coliforms and E. coli).
Coliforms – These bacteria are found in animal waste and sewage, soil and vegetation. Coliforms in drinking water could mean that surface water is entering your well.
E. coli – E. coli belongs to the Coliform group of bacteria and is found in the intestines of humans and animals. E. coli in your well water could mean that animal or human feces are entering your well from a nearby source, such as a septic system.
If these indicator bacteria are found in the sample, other harmful microorganisms could also be present. The water may be unsafe to drink.
The following table will help you to understand your test results:
| Organisms |
Ontario Drinking Water Standards Interpretation |
Reason |
Total Coliforms per 100 ml
E. coli per 100 ml |
5 or less
0 |
No significant evidence of bacterial contamination |
3 samples, taken 1-3 weeks apart are needed to determine the stability of water supply. |
Total Coliforms per 100 ml
E. coli per 100 ml |
> 5
0 |
Significant evidence of bacterial contamination. |
May be unsafe to drink. For information immediately, contact Halton Region's Health Department for information immediately. |
| E. coli per 100 ml |
> 0 |
Significant evidence of bacterial contamination. |
Unsafe to drink. Evidence of animal or human waste contamination. Contact Halton Region Health Department for information immediately. |
| NDOGN - No Data: Overgrown with Non-target: |
Significant evidence of bacterial contamination. |
May be unsafe to drink. For information immediately, contact Halton Region's Health Department for information immediately. |
| NDOGT - No Data: Overgrown with Target: |
Significant evidence of bacterial contamination. |
Unsafe to drink. Evidence of animal or human waste contamination. Contact Halton Region Health Department for information immediately. |
What to do if your well water is not safe to drink due to bacteria contamination?
- Ensure you have a safe drinking water supply.
- Bring your well water to a rolling boil for at least one minute and let it cool before using it for drinking, making infant formula, juices, ice or recipes, brushing your teeth, rinsing contact lenses, and washing food or dishes. Refrigerate your boiled water until it is used.
- Use bottled water from an approved source or municipal supply.
- Do not drink your well water until you receive three results, taken one to three weeks apart, reporting “no significant evidence of bacterial contamination”.
- Find and remove the source of contamination.
- If you have a water treatment system or device, ensure it is operating properly. You may need to consult with a water treatment professional.
- You may need to disinfect your well after the source of contamination is addressed.
- If your drinking water quality does not improve, consider:
Contact the Health Department for advice on the steps you can take to address well water quality problems.
How to test your well water for chemicals
The Health Department will test well water for nitrates free of charge. Please contact the Health Department to arrange for a nitrate test.
Other chemical testing is offered through private accredited and licensed laboratories. For more information, please see the Government of Ontario’s list of Licensed Laboratories.
Contact the Health Department if you have questions about chemical testing or if you require assistance to understand your well water test results.