Shock chlorinating a well is done by introducing a chlorine solution into the well casing, and circulating the solution in the system. Ordinary liquid 5% laundry bleach will work. Use one gallon of bleach diluted with four gallons of water from the well. If a clean, five gallon container is not available, you can mix the solution using one quart of bleach to each gallon of water.

Pour the mixture into the well casing - into the pump or drop pipe. Dug and bored wells that have become contaminated should be pumped down as far as possible, and cleaned, before allowing the well to fill with water and disinfectant. After dosing with the disinfectant, start the pump and open all taps, one at a time, until the water from each tap (including outdoor faucets and hydrants) has a distinct chlorine odor. Use as little water as possible during the following 12-24 hours. Short showers and flushing toilets is ok, but do not drink the water, or use it for cooking or laundry. Following the 12-24 hour time period, pump chlorinated water through an outdoor faucet, to avoid overloading the private sewage disposal system. Do not pump the well dry. Request another sample two weeks after the date of chlorination, or sooner, if all traces of chlorine are absent.

Water which has been bacteriologically tested and found unsafe for drinking and food preparation should not be used unless it is boiled for five minutes, or treated with laundry bleach at a rate of three drops per gallon of water, or three tablespoons per one hundred gallons of water. If this does not produce a strong taste of chlorine in the water, increase the quantity of chlorine, until a strong taste is produced. The chlorine-treated water should stand for thirty minutes before being used. If repeated chlorination does not give satisfactory results, it may be necessary to install a mechanical chlorinator before further use, or, the water supply may need to be abandoned for any domestic use, and a new water source developed.

CAUTION: when working with chlorine, persons should be in a well-ventilated place. The strong chlorine solution should NOT come in contact with skin or clothing. Solutions are best handled in plastic containers, because metals are corroded by strong chlorine solutions.

Make Sure your water is safe...a safe water supply costs very little, compared to your greatest asset: your health. For more information, call 431-2662, or contact the EH Director

last updated 8-16-05