How to Shock a Well


To find a small degree of pollution in private wells on the first test is a common occurrence which, in many cases, is easily remedied.

Three typical occurrences are:

  1. The well may have been opened to clean it, and a disinfection treatment was not made on the system upon completion of the work.
  2. When a new pump or new pipe is installed, bacteria from the soil or contamination from other sources may get into the water system.
  3. Surface water may have flooded over the well cap or cover or otherwise seeped into the water system.


Remove the cap or cover from the well casing.

  1. Mix 2 quarts of bleach in 10 gallons of water. Pour the solution into the well.   Using a hose, recirculate the water back into the well for at least an hour, then close the tap.
  2. Run all inside and outside cold water taps until chlorine odor is detected, then shut them all off.  If you have a water treatment system, switch to bypass before running the faucets
  3. Mix 2 more quarts of bleach in 10 gallons of water and pour this chlorine solution into the well. Replace the wellcap.  Allow The well to stand idle for at least 8 hours and preferably 12 to 24 hours.
  4. Using a hose on an outside spigot, pump the well to waste, away from grass, shrubbery, streams, ponds, and septic tanks until the odor of chlorine disappears.
  5. Retest for bacteria 7 to 10 days after disinfecting.

The information and recommendations contained herein are, to the best of OCL’s knowledge and belief, accurate and reliable.  This document is offered in good faith.  OCL does not warrant or guarantee accuracy, reliability, or completeness.  It is the user’s responsibility to satisfy himself as to the suitability and completeness of such information for his own particular use.  We do no accept liability for any loss or damage that may occur from this information.