All wells recently constructed, repaired or not conforming to accepted standard of bacteriological purity, should be thoroughly disinfected and sealed before being put into use. The well should be first pumped to remove or lower turbidity to make the disinfecting treatment more effective. Disinfect the well as follows.

  1. CHLORINATING AGENT: Use any of the common household liquid bleaches containing 5% chlorine. For wells producing 10 or more gallons per minute, use 1 cup of granular chlorine. (i.e. swimming pool chlorine).
  2. PREPARATION OF SOLUTION:Dilute 1/2 gallon of bleach in 3-5 gallons of water for every 50 feet of well casing. Just remove the screened bend vent and pour the mixture into the well. Make sure the walls of the casing are washed down with the chlorine solution. Larger doses (within reason) are not harmful.
  3. SOLUTION CIRCULATION: To insure that the chlorine mixture reaches the entire length of the casing, attach a hose to a tap nearest to the well, preferably at the pressure tank, and insert the other end of the hose down into the casing. Turn on the tap and allow the water to circulate for 1/2 hour. Before circulating make sure the chlorine solution has filled the hose by running until chlorine odor is noted.
  4. Circulate the chlorine mixture through the water lines making certain that every outlet (bathroom sink, tub, kitchen sink, outside taps etc.) has been opened and chlorinated water allowed to flow through. Allow the system to set at least 8 - 12 hours without any usage. Then open outlets and allow the chlorinated water to be pumped out of the well..
  5. After normal usage of the water for at least 5 days the well should be resampled.
To protect a well supply from surface contamination, a sanitary well seal should be placed on the top of the well. If possible, the pump should be placed on the top of the well, as to prevent water, oil drippings, and incidental contamination from running back into the well. If the sample following the chlorination shows contamination, please contact the lab to determine what types of treatment might be necessary.