A contaminated well can be disinfected using chlorine, either in the form of regular household bleach (do not use a formulation which includes any type of fragrance), or the use of 70% sodium hypochlorite swimming pool chlorine tablets (do not use any tablets which contain stabilizers).
Caution: Chlorine is a highly corrosive chemical, especially in concentrated form. Read labels and always use proper safety precautions:
- Wear safety goggles, rubber gloves, and an apron to protect your clothes from splash.
- Always work in a well-ventilated area.
- Never mix chlorine with other chemicals or detergents. Chlorine can mix with these products to form a highly dangerous gas.
While there are formulas for determining the precise amount of chlorine to use for disinfection, many homeowners do not know the depth of their well, making calculations difficult. One gallon of household chlorine bleach or 1 pound of chlorine tablets will adequately disinfect the average well in our area. If you have an extremely deep well, over 600 feet, you may use an extra half gallon of bleach, or ½ pound of tablets. Chlorine tablets are preferable for wells over 400 feet, where they will sink to the lower depths more readily.
After removing your well cap or cistern cover; use the following procedure to disinfect your well:
- In a plastic 5 gallon bucket, mix the liquid bleach with water and pour the solution into the well. If using tablets, pour them down the sides of the well. Replace the well cap or cistern cover.
- Inside your home, run all the water faucets, showers, bathtubs, laundry connections and flush all toilets until you begin to smell chlorine. For deeper wells, you may wish to place a garden hose that has been connected to 1 of your outside faucets into the well and recirculate the water for 2 hours. This will help to mix the chlorinated water deeper into the well.
- When you begin to smell chlorine, shut off all the water and allow the chlorinated water to stand in the pipes for at least 12 hours or overnight.
- After twelve hours have passed, or the next morning, you will need to flush the water system until the chlorine smell and taste is gone. If you are on a septic system, do not allow the water to run into your drains or it will kill the bacteria in your septic tank, which help to break down waste. Instead, run the chlorinated water through a garden hose into a ditch or storm drain. Avoid running it onto grass or ornamental shrubs or flowers.