How to Disinfect a Water Well

How to Disinfect a Water Well


1. Obtain 2 gallons of household bleach (5.25% chlorine) - bleach begins to lose its effectiveness after being on a shelf for 30 days. Shut off power supply to well. Place water softener on by-pass. Remove the well cap or the vent pipe or plug if the well is equipped with a sanitary well seal. Pull the electrical wire connectors up and out from inside the well.

2. Pour 1 gallon of household bleach directly into the well. You may choose to add 1 gallon of white vinegar to the well. Pour bleach all along inner edge of well casing to disinfect inner surface of casing.

3. Turn on power supply and connect a hose to the house spigot and run water directly into the well until a chlorine odor is present in the water. Run the water this way for 15 minutes. Make sure the water runs down all surfaces of the inside of the casing to properly disinfect the entire interior (a nozzle helps to wet down all the inside of the casing).

4. Shut off water supply to hose and go to each water fixture and water using appliance (with the exception of water softeners and similar water treatment devices) inside and outside the house and run it until a chlorine odor is present and then shut it off and go to the next one. Proceed in this manner until all plumbing contains bleach (manufactures of water softeners and other water treatment devices should be contacted for specific chlorination instructions for their device to avoid potential damage). The water softener should be fully regenerated prior to the chlorine treatment. Reverse Osmosis units and carbon filters should be on by-pass during shock chlorination and sampling. To be positive that all chlorine is reaching all the plumbing you may want to obtain some chlorine test strips to check the water. The test strips can be found wherever swimming pool chemicals are sold.

5. Shut off electric supply to well and close all valves and pour another gallon of household bleach directly into the well. You may choose to add another 1 gallon of white vinegar at this time. The water must sit 8 hours if you use the white vinegar method, if not using white vinegar, leave all valves closed for at least 24 hours or longer (toilets may be flushed if needed). Recap the well or replace the vent pipe or plug. Turn on electric.

6. Open the hose spigot and discharge water to ground surface or drainage ditch until chlorine odor disappears. Open every house hold fixture and let water run until the chlorine odor is gone. To be positive that chlorine has been removed from all the plumbing you may want to use the same chlorine test strips as above to check the water.


The well should now be properly disinfected. Please contact the Logan County Health District to schedule a water sample at (937) 592-9040 ext. 6206.

For more assurance that your disinfection has been effective, you may want to wait 2 weeks or more to have your water re-checked.