How do I chlorinate my well?

The process of chlorination hasn’t changed that much over the years, but the chlorine products and the tools to measure concentration (in parts per million (ppm)) have. Currently, test strips are used to ensure that a sufficient amount of chlorine has been added to produce a concentration of greater than 125 ppm and less than 200 ppm. If a concentration of greater than 200 ppm is used, E. coli and Coliform may be removed but other contaminants may be released from the aquifer. Excess chlorine also deteriorates the well casing.


Information needed to properly chlorinate your well:

  1. How deep is your well?

  2. What is the depth of your water table?

  3. What product are you using?

  4. What is volume of the aquifer your well is in?

Ex) The well depth is 140 feet and the water table is 40 feet down; the product is 73% calcium hypochlorite: 140 – 40 = 100 foot column of water; 1/3 of a cup will bring this much water over 100 ppm (assuming that the aquifer doesn’t expand much beyond the end of the pipe).


Chlorination Procedure

Note: USE CAUTION WHEN CHLORINATIING YOUR WELL SYSTEM! If your well has not been chlorinated in past eighteen months, we DO NOT recommend chlorination without assistance due to the quantity of iron and lime that may become solvent.

  1. SHUT THE POWER OFF TO PUMP & BYPASS ALL CONDITIONING UNITS!!

  2. Remove the well cap (typically 1/4” bolts). Inspect the gasket for damage and replace it if needed.

  3. If possible, gently move the wiring to side of casing.

  4. Acquire the correct amount of chlorine tablets needed to bring you well water to 125 ppm.

  5. Dissolve the tablets in four gallons of water. Do not allow the tablet solution to sit for more then 12 hours.

  6. Pour the chlorine water into the well.

  7. Return power to the pump and bypass.

  8. Using a hose, run water into the well for at least 20 minutes.

  9. Let the chlorine solution stand for a minimum of eight hours – 24 hours is better.

  10. Run one or more outside hose bibs onto the ground for at least eight hours, or until the water is clear and the pungent chlorine odor has subsided. You may notice that the water has become discolored due to the iron, lime, and other deposits which the chlorination broke loose.

Note: Do not continue to run your well pump if water doesn't flow – shut off the pump circuit breaker and call the pump tech for help.

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