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.
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
- 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.
- 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.
- Depending on the type of wellhead, you can either remove the cap from your well or remove the threaded plug from the cap.
- 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.
- Pour a 4-litre bottle of unscented household bleach into the well.
- 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.
- Once you have poured the bleach into the well, start the pump.
- Turn on the taps in the house or building and let the water run until you can smell bleach.
- 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.
- Let the bleach mixture sit in the well and pipes for at least 6 hours, or overnight if possible. Do not drink this water.
- After the waiting time has passed, turn on the electricity to the pump.
- Attach a garden hose to the outside tap.
- Open the tap and let the water run until the smell of bleach is gone or hardly noticeable.
- 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.
- After 1 week, have your drinking water re-tested for bacteria.
If you have questions about disinfecting your well, email firstname.lastname@example.org, 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.