To treat well water with bleach, use a pump to clear the well of any dirty or cloudy water, and then add chlorine bleach to the well. This bleach is not found in the supermarket and must obtained from a professional who sells water treatment products.
The amount of bleach needed depends on the size of the well. For example, a well 10 feet deep and 32 inches in diameter requires 3 quarts of chlorine bleach. Mix the bleach with 5 to 10 gallons of water, and carefully pour it into the well. Use water from a garden hose to help the mixture circulate around the well. When you detect a strong smell of chlorine, turn the hose off, and cap the well.
Next, turn on the faucets in the home one at a time. They should be allowed to run until there is a strong smell of chlorine. When this happens, turn the faucet off, and turn another faucet on. This may take a while, but do not let the water run indefinitely. Let the water sit undisturbed for at least 8 to 12 hours, and then purge the water of most of the chlorine, either by allowing it to run into the sewage system or by pumping it out of the well and disposing of it. Retest the water for pathogens.