Well Chlorination Procedure

This procedure is for wells not chlorinated before or wells infected with bacteria.

First, a little chemistry: Calcium hypochlorite (pool shock) does not itself kill bacteria. The shock reacts with water forming an acid called hypochlorous acid. This acid is the most effective agent for killing most forms of bacteria. It does this by disrupting the bacteria nuclei. For this reaction to be most effective, the pH of the well should be less than 8. That is because hypochlorous acid forms hypochlroric acid, which is a much less effective bactericide. Eventually, this further goes on to form hypochlorite, which is an even weaker bactericide. To try and keep as much hypochlorous acid in contact with the bacteria, we have broken up the chlorination procedure into two equal steps.

Before performing this procedure, test the pH of the well using the test strips provided.

If the pH is above 8, add 1-2 hours to each step outlined below.

  • Turn off power to the well pump.
  • Remove the well cap.
  • Pour 1/2 of the bag of pool shock into a bucket of water and stir until mixed.
  • Bypass any water filtration systems present.
  • Pour the mixed solution of shock down the well shaft.
  • Take a hose attached to an outside faucet and place about 3-4 feet down the well casing.
  • Turn on the water (about 1/2 force) and allow the water to circulate in the well. This aids both mixing and exposure of the acid formed to react with bacteria.
  • After several minutes (≅10), open faucets in the house and run until you smell chlorine. Then shut off. Leave off for the remainder of the procedure.
  • After approximately 3 hours, remove the hose from the well and let the water run out onto the ground until you no longer smell chlorine. The water may be highly colored, but this is normal.
  • Repeat the procedure with the remaining shock, mixing and pouring into the well and replacing the hose.
  • Let the well recirculate for an additional 3 hours.
  • After 3 hours, remove the hose, run out onto the ground.
  • Turn on all the taps inside the house and run until there is no more chlorine odor.
  • Retest for bacteria about 3-4 days after this procedure.

Note: if you have a water softener, this may be chlorinated by pouring a half cup of unscented bleach into the salt tank and going through a backwash.

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