Well Disinfection

If you have had your well tested and found that it has failed for certain kinds of bacteria, you may be able to treat the bacteria by disinfecting or "Shock Chlorinating" your well.

What You'll Need:

  • An ordinary garden hose, long enough to reach from the nearest outside faucet to the wellhead.
  • A funnel
  • Ordinary household bleach, any brand will do.
  • A measuring cup

To properly disinfect the well, you will need to add 1-1/2 cups of bleach for every 100 gallons of water.

For 4" Wells - There is 0.65 gallons of water per foot

For 6" Wells - There is 1.5 gallons of water per foot

For 8" Wells - There is 2.5 gallons of water per foot

So for example: A 4" well with a depth of 400 feet has .65 x 400 = 260 gallons of water so approximately 3-1/2 cups of bleach should be used.

If you have a storage tank system to supplement your well, be sure to add the volume of those tanks to your calculation.

Start by diluting the bleach in 4-5 gallons of water. Next remove the vent plug from your well seal. If your seal does not have a vent opening, you may have to remove the seal in order to pour the bleach solution down the well. If your well is a shallow well, and you have an above ground jet pump, this process should be fairly simple. However if it is a deep well with a submersible pump it can be much more difficult. In this case it's recommended to call a professional because if it's not done properly, it could result in costly repairs and possibly fishing your pump from the bottom of your well.

Next, insert the funnel into the vent plug and pour the bleach solution completely down the well. Once all the bleach solution has been poured out, remove the funnel and place the end of the garden hose in the vent hole. Open the faucet which is connected to the garden hose and run the water for 30-40 minutes to allow the chlorine to completely mix with the water inside the well (and inside the storage tank if you have one).

After running the water 30-40 minutes turn off the faucet. Now inside the house, turn open one of the faucets until you can smell chlorine coming out. Then close the faucet. Repeat this for every faucet in the house. (Note: you can also use chlorine test strips to help determine if chlorine is present).

In order to ensure that the chlorine kills all of the bacteria, it must set in the plumbing at least over night. The longer you can leave it however, the better results you'll get. We recommend at least 24 hours.

Once the chlorine has had enough time to completely disinfect the plumbing, it's time to flush it out of the system. Turn each faucet on inside the house until you don't smell chlorine anymore. (As above, you can also use chlorine test strips to ensure all chlorine is gone from the system.)