Disinfection: How to Kill the Germs in Your Well

Disinfect (sanitize) your water to kill germs before using the water for any household purposes. Even if your well is working, you should use other sources of water for drinking, food preparation, and brushing teeth until your well test results show the water is safe to drink. Check with local health department personnel about other acceptable sources of water.

A concentrated bleach solution needs to be circulated through the well and house plumbing to assure proper disinfection of the well and plumbing before use of the well water. Below is a step by step method to sanitize a well before restoring it to full use. If your well is a “point well”, or if the well pump is a jet pump, it is recommended that you hire a water well contractor to disinfect your well.

ELECTRICAL SAFETY -- EXTREME CAUTION is advised when disinfecting a well.

Electricity near water can be dangerous. Before you do anything to the well:

  • Shut off power to the pump and water system.
  • Examine for broken wire insulation or missing wire nuts and repair as necessary.
  • Wear rubber-soled shoes or boots, preferably waterproof.
12 Steps to Disinfect Your Well
Step Instructions
1 Attach a hose to the outdoor faucet that is closest to the well or pressure tank. The hose needs to be long enough to reach the well. Run water through the hose until it is clear.
2 Mix 2 quarts of regular, unscented household bleach with 10 gallons of water in a large bucket in the area of the well casing. Do not use “splashless”, scented, or gel variety bleach.
3 Turn off the electric power to the well pump (the switch is probably located at the circuit breaker box or near the pressure tank). Carefully remove the well cap (and well seal if there is one). Set aside.
4 Turn the electric power to the well pump back on. Place the other end of the hose into the casing. Turn the faucet with hose on.
5 Pour 10 gallons of the water and bleach mixture down the open well casing while the water is running through the hose. Continue running the water through the hose placed inside the well casing.
6 Run the water at each indoor and outdoor faucet until a chlorine odor is present, and then shut off each faucet (except the faucet with the hose).
7 Continue running water through the hose and down inside the well casing to recirculate the chlorine solution. Use the hose to also wash down the inside of the well casing.
8 After one hour of recirculating the water, remove the hose from the well. Fill a bucket with 10 gallons of water. Shut off the faucet that the hose is connected to and make sure all the other faucets are still shut off to assure the pump is stopped. Remove the hose from the well.
9 Mix two more quarts of bleach in 10 gallons of water. Use about half a gallon of the mixture to rinse and disinfect the well cap (and seal if there is one). Turn off the electric power to the well pump. Pour the remaining mixture into the well. Replace the well cap (and seal).
10 Allow the well to stand idle for at least 8 hours, preferably 12 to 24 hours. Avoid using the water during this time. The electric power to the pump still needs to be off.
11 Turn the electric power to the well back on after it has been idle for 8 to 24 hours.
12 Purge the well and plumbing of the chlorinated water:
  1. Connect a hose to an outside faucet and place the other end of the hose away from grass and shrubbery.
  2. Open the faucet and run the water until the chlorine odor disappears.
  3. Open all the other indoor and outdoor faucets until the chlorine odor disappears.