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Disinfecting A Well Contaminated With Bacteria and/or Hydrogen Sulfide Odors

I recommend using hydrogen peroxide instead

"I think it's absolutely crazy to pour bleach down a well."

ecologist James P McMahon

Here's one way, using bleach:

The following is a state suggested formula for using common household bleach to disinfect a well:

  1. Remove well cover.  Pour the required amount of bleach into the well.  SEE TABLE BELOW.
  2. Run ALL faucets in the house, one at a time, until you smell the chlorine at the faucet.
    This ensures that the whole system will be disinfected.
  3. Connect a garden hose to an outside tap or an indoor tap with the correct thread fitting.  Put the other end of the hose into the well, turn on the faucet, and from time to time move the hose so that the chlorinated water bathes the sidewalls of the well casing.  Do this for at least six hours.  Turn off tap and remove the hose from the well.
  4. Replace the well cover.
  5. DON’T USE THE WATER for at least twelve hours.  Forty-eight hours in optimal.
  6. Run the water to waste but NOT IN THE SEPTIC SYSTEM for several hours, or until the chlorine  taste is dilute enough to be unobjectionable.  The best way to run the water to waste is to use the  garden hose mentioned above (item 3).  Direct the hose into an area where the chlorinated water will not cause environmental damage or affect the water supply of others.  For a typical well, this may take 3-4 hours.

    NOTE:  To avoid pump overheating and possible damage, turn off the water when flow is at a trickle and wait at least 15 minutes before turning on the pump again.
  7. After a week of use, retest for bacteria.
  8. In some cases, one chlorination treatment WILL NOT be sufficient.  Repeat disinfection procedures as needed.  You can also use calcium hypochlorite granules to provide a continuous release of chlorine in your well.

Be sure to have a whole house KDF/Activated Carbon filter in place if you’re going to add chlorine to your well.  You can use a by-pass valve to circumvent it when disinfecting the house pipes.


                      Well Depth                                 Amount of Liquid Household Bleach

                       Up to 150 ft                                                   One Quart

                       151 to 300 ft                                                  Two Quarts

                        over 300 ft                                       One Gallon and 1 cup crushed                                                                                          swimming pool tablets


Source: Ohio Department of Natural Resources


* My comments:

It is my opinion that you can never entirely disinfect a contaminated well.  The method above is the very traditional approach to trying to eliminate bacteria from a well. But it's not enough chlorine. Think about it.  You're using chlorine to attempt to eliminate every single individual bacteria.  No.  What you're doing is buying some time. The population will slowly rebuild. When you use chlorine you also release dangerous trihalomethanes and haloacetic acids into your household water.  These are very dangerous but can be removed with the proper filtration.


Here's another way - using hydrogen peroxide:

I recommend using hydrogen peroxide to disinfect a well instead chlorine

Both are oxidants.  Hydrogen peroxide does not last as long in the well.  It dissipates, converting to water and oxygen.  Thus, you may have to repeat the treatment more often, but the byproducts are not hazardous.  Apparently though if you have bromides in your well it can convert these to bromates which do have health impacts.  As always, it is best to test before proceeding. The following instructions provide a thorough disinfection. I provide a formula for determining how much hydrogen peroxide to use. I do not sell hydrogen peroxide and have no affiliation with any sellers.

I have instructions for disinfection using hydrogen peroxide for $50. This is for bacteria and hydrogen sulfide odors only.

If you have iron in your water don't buy this!  

Instructions for Treating a Well using Hydrogen Peroxide

Don't call me to ask how much hydrogen peroxide to use. Buy my instructions. It takes a lot more hydrogen peroxide to disinfect a well than it does bleach. And hydrogen peroxide is very expensive. If you're not willing to pay a lot of money for it, then don't buy my instructions. Use bleach instead. People who buy my formula complain about the cost of the peroxide. There's nothing I can do about that. I don't sell hydrogen peroxide nor am I affiliated with anyone who does. If you have iron in your water or iron pipes this method may cause rusty water. If you have iron or manganese then don't buy these instructions!

After you pay for it I will email the pdf to you

Some people recommend the use of calcium hypochlorite granules to provide slow release of chlorine in a well to control bacteria, iron, or hydrogen sulfide odors.  This will also provide a constant source of carcinogens.

I try to stick with all natural non-toxic methods whenever possible.

If you have a problem with bacteria I would recommend that you also install a 5 micron filter, followed by an Ultra Violet light.  This will kill the bacteria as they enter your home. You may email me for specs and pricing on a UV light.

Further thoughts....

Be aware of activities in your community that can put your drinking water at risk.  Talk to your neighbors to determine if problems with your drinking water are individual or community-wide.  Check out the history of the area in which you live to determine if past activities are having a present impact on your drinking water.

And manage your own septic tank if you have one.  Replenish it on occasion with bacteria (I use Roebic K-37, which you can buy at any hardware store) to aid in digestion and limit your use of chemicals in the house, such as bleach, Lysol, and other sanitizers, that will kill the bacteria in the septic.  Visit my link on using natural cleaning products to learn more.

Learn more about well water testing and well water treatment systems.


You may return to my water purification products and services here:

Water Products, Water Tests, and Services


James P McMahon in Zion National Park
James P McMahon

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 "When you drink the water, think of the spring"

You want the best water you can get. That takes careful consideration and it may take expense.



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