Disinfection of a well is recommended to eliminate disease causing organisms and other organisms, which can and sometimes do grow in wells. A well should also be disinfected following repair, maintenance or replacement of the pump or water lines and at times of flooding. For a new well, disinfection should be conducted following development. In the event that there is a delay in pump installation, interim or partial disinfection should be undertaken.
How do I disinfect my well?
Disinfection generally involves the following steps:
Remove the threaded access plug located on top of the well. Place a funnel in this entry port and pour domestic or household bleach such as Clorox, Purex, etc. into the well. Next, connect a garden hose to a nearby faucet and wash down the inside of the well.
Use the following as a guideline:
Well Depth Amount of Liquid Household Bleach (5%)
Up to 150 ft One quart
151 to 300 ft Two quarts
Over 300 ft One gallon
Wait 30 minutes and then open all faucets until the odor of chlorine is detected at water outlets, including faucets or fittings, sprinklers, drip lines, irrigation lines, shower, dishwasher, toilets, etc. Swimming pool test kits or test strips can verify the presence of chlorine at these sites.
Close all outlets and allow water to remain undisturbed in the water lines and well, overnight or longer. Restrict water usage during these hours.
The following day, open outlets until no chlorine odor can be detected. The water supply should then be free of chlorine. Swimming pool test kits or test strips can verify the absence of chlorine at these sites. *(see note)
Sample the water for bacteriological quality two (2) or three (3) days after flushing.
If bacteria are still detected, the water may be unsafe to drink. Contact a pump company, a well driller or the health department to discuss further options. After discovering the source of contamination and the problem has been resolved, disinfect and resample.
*NOTE: Disposal of the chlorinated water should be away from trees, shrubs, or lawns and into storm sewers, drainage ditches, etc. Such water should not be flushed into plumbing systems of homes that use individual septic tanks.
