How could I Chlorinate a well?*

These instructions are provided as a courtesy by Cribley Drilling Company, Co. based on our experience with well chlorination. There is no guarantee and it is possible you may have to repeat this process. Cribley Drilling Company Co. accepts no responsibility for the outcome. Proceed at your own risk.

  1. Put water conditioner on by-pass and if you have a reverse osmosis drinking water system shut off its feed water valve. This will protect them from being damaged by the chlorine.
  2. Turn power to the well pump off.
  3. Remove the well cap. (If the well cap has three or four set screws around the top this is a job you can do yourself. If it has one large bolt in the center of the cap, you should not attempt to remove the cap. Get a licensed well contractor to do it for you.) if you are in doubt, get as much information off the top of the well as you can, give us a call, and we’ll attempt to give you an answer as to whether you should attempt this yourself or not.
  4. For a steel casing well use approximately one cup granulated chlorine. We do not recommend using liquid chlorine bleach on steel casing because it can break loose corrosion from the side of the casing which might be sucked up into the pump and seize it up. Most hardware or pool supply stores carry this type of chlorine or you can stop by and pick it up at our office.
    Chlorinate Well FAQ graphic
    For PVC casing wells you can use either the granulated chlorine or two gallons of liquid chlorine bleach.
    You will be adding the chlorine to the annular space (see figure 1 & 2) without getting any on the wire nut connections at the top of the well. Do not put chlorine in the center hole (FIG. 1) or in the center pipe (fig. 2) because this is a dead end so the chlorine will not get into the water.
  5. Put the cap back on the well
  6. Turn the power to the well back on
  7. Hook up two hoses outside and let the water run until you can smell chlorine. (The purpose of using two hoses is so the pump will run continuously instead of cycling on and off.) when you can smell chlorine outside, turn the hoses off and run all the faucets in the house until you can smell chlorine. Turn faucets off and let chlorinated water sit in the plumbing lines for 12-24 hours. During this time you should not drink, bathe, wash clothes, or cook with the chlorinated water but you can flush the toilet with it.
  8. The next day you need to run the water long enough to purge the system. Start by running the hoses again until you can no longer smell chlorine outside. Then turn off the hoses and run all faucets inside until you can no longer smell chlorine. If you are chlorinating the well in order to take a coliform bacteria water sample, make sure you have the chlorine thoroughly purged from the system before you take the sample. If the lab detects chlorine they will not test your sample. Purging the chlorine from the system can take anywhere from two to six hours. There is no way to know how long it will take. Run it until you can no longer smell chlorine.
  9. If you are taking a coliform bacteria water test, take it now while following the tips below and with the water conditioner still on by-pass. If you are not going to take a sample you can take the take the water conditioner off by-pass and if you have a reverse osmosis drinking water system turn it back on as well.

If you need help, call cribley for service.

Austin Clark

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