Chlorination & Disinfection of Water Wells

This procedure should be done in late evening or early morning, if you will be gone all day and not utilizing the water. This will allow the chlorine in the system for six (6) to eight (8) hours, which is the preferred amount of time.

  1. By-pass the sofener/filtration system, if possible.
  2. Remove the well cap. Check the well seal at this time and replace any worn or damaged parts. Remember that a proper seal is vital to prevent contamination. If this is a buried well, breaking the seal requires that the well be brought up to the current code. Check with the Kankakee County Health Department regarding permits, fees, and requirements.
  3. For each 100 gallons of water in the well, use three (3) cups of chlorine (household bleach) or two (2) ounces (4 tablespoons) of hypochlorite granules. Use the following guidelines to help determine well volume:

    Well Diameter
    (in inches)
    (per Foot Depth)
    3 0.37
    4 0.65
    5 1.0
    6 1.5
    8 2.6
    10 4.1
    12 6.0
    Amount of Disinfectant Required for each 100 gallons of Water
    Laundry Bleach:
    (5.25% Chlorine)
    Hypochlorite Granules:
    (70% Chlorine)
    3 cups 2 ounces
    1 cup = 8 oz. measuring cup
    (2 cups = 1 pint, 4 cups = 1 quart)
    1 ounce = 1 heaping tablespoon granules
    16 ounces = 1 pound
  4. Mix the total amount in about five (5) gallons of water. If dry granules are used, they should be mixed into solution before adding to the well. Pour the solution into the well.
  5. Using a garden hose, run water from the hose down the inside of the well until a strong smell of chlorine is evident.
  6. Replace the well cap.
  7. Run each cold water faucet in your house until you are able to smell chlorine in the water. Do not use water for drinking or cooking.
  8. Allow the chlorine to sit in the system for six (6) to eight (8) hours, which is the preferred amount of time.
  9. Flush chlorine from system by running outside faucet through hose for one (1) hour or longer, until water runs clean and all chlorine smell is gone. Flush from inside plumbing until all smell is gone.
  10. Return softener/filtration system to service.
  11. Take a water sample one (1) day after well has been chlorinated to assure proper disinfection has been completed.

Please note: chlorine bleach is a dangerous and hazardous chemical compound and should be treated with full respect and caution. Follow all necessary precautions and safety procedures. We recommend that any chlorination procedure be performed by a certified, qualified professional. We are not responsible for any situations, repercussions or costs that may be related with this basic advice on procedure.

For Further Information Contact:

Kankakee County Health Department
2390 W Station St
Kankakee, Illinois 60901
Phone: (815) 802-9400
TDD/TTY: (815) 802-9312