Learn how to disinfect your drinking water well

You can disinfect your drinking water well using household bleach. It contains chlorine, typically 5.25% sodium hypochlorite. This is an effective, easy-to-use and generally safe disinfectant for wells.

It's common for drinking water wells to become contaminated with disease-causing bacteria. This creates a serious risk to the health and wellbeing of you, your family and your visitors.

You should test your well at least once a year for the presence of bacteria.

When to disinfect your well

You should disinfect your well if:

  • a laboratory test shows bacteria to be present in your well water;
  • you have carried out maintenance or repairs to your well;
  • you want to use a well which has been unused for a long time or is only used on occasion or seasonally;
  • you note a change in the taste or odour of the well water; or
  • your well has been flooded.

Handling bleach

To help to protect your skin and eyes when handling bleach, you should:

  • wear rubber gloves;
  • wear safety glasses;
  • avoid inhaling fumes;
  • keep children and pets away; and
  • follow the safety instructions on the bleach bottle.

How to disinfect your well

  1. Disinfecting your well will take 6 to 12 hours. Before you begin, be sure to save enough water in clean containers to meet your needs. You will not be able to use your well until you finish.
  2. Turn off the well pump by shutting off the electrical circuit breaker.
    • There's a risk of electrocution if you do not turn off the power.
    • Be careful to protect yourself and others that may help you with this process.
    • Someone could unknowingly turn the power back on while you're working.
    • Place a label or a piece of tape over the breaker switch.
  3. Depending on the type of wellhead, you can either remove the cap from your well or remove the threaded plug from the cap.
  4. If your well head is located in a pit, do not enter it if at any time your head will be lower than its top edge.
    • Even a shallow pit can be extremely hazardous due to a lack of oxygen or the presence of poisonous gases.
    • If your well cap is in a pit, hire a company with staff who are specialized, trained and equipped to work safely in the pit.
  5. Pour a 4-litre bottle of unscented household bleach into the well.
  6. Let the bleach run down and coat the inside of the well casing completely.
    • If you have a water softener, bypass it before you begin.
    • The high-strength bleach mixture may damage the softener.
  7. Once you have poured the bleach into the well, start the pump.
  8. Turn on the taps in the house or building and let the water run until you can smell bleach.
  9. Once you notice the bleach smell, turn off the taps and shut off the pump. If your well is very deep, it may take a long time for the bleach to reach the taps.
  10. Let the bleach mixture sit in the well and pipes for at least 6 hours, or overnight if possible. Do not drink this water.
  11. After the waiting time has passed, turn on the electricity to the pump.
  12. Attach a garden hose to the outside tap.
  13. Open the tap and let the water run until the smell of bleach is gone or hardly noticeable.
  14. After running water from the outside tap, open the inside taps and let the water run until the smell of bleach is gone or hardly noticeable.
    • Be sure to keep the water away from the well, people, animals and water bodies (for example, lakes, streams).
    • As chlorine is deadly to fish, do not allow chlorinated water to drain into any place where fish might be.
  15. After 1 week, have your drinking water re-tested for bacteria.

If you have questions about disinfecting your well, email environmental.health@yukon.ca, phone 867-667-8391, toll free in Yukon 1-800-661-0408, extension 8391, or visit Environmental Health Services at #2 Hospital Road in Whitehorse.