Testing Your Well Water
You can view and download this information in pdf form on this factsheet.
Testing at least three times a year for bacteria is recommended by the Ontario Ministry of the Environment and the Ontario Ministry of Health. Test your well in early spring and 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 regularly, even if your water seems fine, because you cannot always taste, smell or see bacteria or other contaminants.
- Select a tap where you can remove aerator or any other attachments.
- Wash your hands thoroughly.
- Disinfect the end of the tap by holding a small amount of bleach in the bleach bottle cap to the tap.
- Run cold tap water for two to three minutes. (Listen for the pump to complete a cycle if possible.)
- Check the sample bottle’s lid. If the tamper proof ring has separated from the cap use another collection kit.
- Remove the sample bottle lid. Do not touch the bottle lip, inside the lid, or inside the bottle. Do not set the lid down on the counter. Hold it in your other hand while you collect a sample.
- Fill the sample bottle to the indicator line directly from the tap without changing the flow of water.
- Replace the cap tightly.
- Complete the form that came with the bottle.
- Refrigerate the sample after collection (do not freeze) and transport in a cooler with an ice pack.
- Take the sample and form to the laboratory within 24 hours of collection.
You can have the test results mailed to you, or you can pick them up at the lab (with proper ID). You can also access the test results via a toll-free telephone number a few days after dropping off your sample. The test result will consist of two numbers – the first for the total coliform count, and the second for E coli. Coliforms are bacteria commonly found in soil and vegetation. Their presence in your well water indicates that surface water is gaining access to your well. E coli is a bacteria from the intestinal tract of warm blooded animals (humans, other mammals, birds). E coli in your water can be from a malfunctioning septic system or manure pile too near the well. Dog droppings on the lawn or even mouse, squirrel, or bird droppings nearby can result in E coli in your water, especially if the well’s lid is not properly sealed or if there are any other structural defects in the well.
Understanding the Test Results
- If the total coliform count is five or less and the E coli count is zero, the water is considered safe to drink.
- Any detectable presence of E coli means the water is NOT safe to drink.
- A total coliform count between 6 and 80 indicates a problem and may be unsafe to drink.
- A total coliform count greater than 80 means the sample has more bacteria than could be counted (see picture with 19 count).
A single test for total coliform 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 a week apart.
Shocking with bleach (chlorine) - not a substitute for repairing a structrual defect in the well
You may receive instructions to shock the well with bleach (chlorine) if a water sample shows levels of bacteria. Shocking the well with chlorine is a temporary method of disinfection used to eliminate a one-time case of bacterial contamination. Shocking should not be used routinely or repeatedly. It is not a substitute for eliminating an ongoing source of contamination or a defect in your well. Always work with a licensed well contractor to repair any structural defects in your well.
Page last updated on Wednesday, January 11, 2012