Skip to content
Emergency Well Disinfection

Many South Carolinians depend on an individual residential well to provide them with a clean safe drinking water supply. Although normally providing excellent water quality, wells do have the potential to become contaminated during extreme weather conditions. These types of disturbances may allow harmful bacteria to enter the well system. An effective method for ridding wells of bacteria is the process of disinfection.

One way to disinfect a well is by adding a chlorine solution into the well and plumbing system. This type of disinfection method, called chlorination, should kill any dangerous bacteria in the water supply.

Before beginning the disinfection process, check the condition of your well. If you notice any damaged wiring in the area, call a professional to repair the problem before continuing. Also, if you have noticed muddy or cloudy water in the system, you will need to open an outside spigot and let the water run until it is clear and free of sediments.

The materials for disinfecting a well include one gallon of regular non-scented bleach. The bleach should contain a 4 to 6 percent concentration of chlorine. Other needed materials include safety glasses to prevent the bleach from splashing into the eyes, gloves to protect hands, and older clothes in case of spills. The most common form of chlorine used for well disinfection is liquid household bleach.

During an emergency situation, one gallon of bleach is recommended for use is the disinfection process. As with any project where chemicals are used, it is important to read the product label to determine suggested safety precautions.

Now let’s look at an example of how you can disinfect your well. This well utilizes a submersible pump located below ground. You must decide how to pour the bleach into the well. This will be easier if a sanitary seal is in place. A sanitary seal looks like this and can be used to provide a protective capping for the well. Notice that there is an air vent screwed into the top of the seal. This is an excellent location for gaining easy access into the well. If there is not an air vent present, try to find a plug in place of where the air vent would normally be located. Once you’ve determined where to add the bleach, simply remove the plug or air vent and use the opening to pour the bleach down into the well casing.

This is an example of a dug or bored well. Bleach can be introduced into this type of well by first removing the cap or cover and then pouring the bleach directly into the well. If there does not appear to be a way to pour the bleach into your well, contact a certified well driller or a DHEC representative to discuss options available for your type of situation.

Once the bleach has been added into the well, you need to mix it in with the well water. This can be done by attaching a hose to a nearby faucet and directing the water back into the well. You will know when the bleach is thoroughly mixed in with the water because you will be able to smell a chlorine odor in the water coming from the hose. Once you detect the chorine odor, it is time to run the chlorinated water through the entire plumbing system. You do this by opening all faucets inside and outside of the house. When you can smell the chlorine odor coming out of these faucets, turn them off. Let the chlorinated water sit undisturbed in the plumbing system for at least six hours and no more than 24 hours.

During this wait period, it is a good idea to double check the well and be certain that the system is completely closed and sealed. It’s not advisable to use the water for drinking, cooking, washing or bathing purposes during this time. You will need to wait until a significant amount of the bleach has been flushed out of the system before resuming these activities.

Once the 6-24 hour wait period is over, it’s time to flush the bleach out of the system. Open an outside tap and direct the water discharge into a prechosen location. Do not release the chlorinated water into a lake, stream or any area that drains into your septic tank system. Once the chlorine odor is no longer detectable in the plumbing system, you can turn off the outside tap. The system should now be properly disinfected, and the water should be safe for drinking, cooking, washing and bathing purposes.

However, you will still want to have the water tested to verify that the bacteria has been removed from the system. You can receive a sample collection kit from your local county health department or DHEC’s office at 2600 Bull Street in Columbia.

Because the water supply has to be completely free of chlorine prior sampling, wait 7 to 10 days before testing for bacteria in a well that has recently been disinfected. In some cases of extreme contamination, more than one disinfection treatment may be necessary to remove all of the bacteria from the system. It should also be noted that recurring water quality problems could indicate a problem with the well’s construction or location.

Before ending, let’s quickly review the disinfection process:

  • Remember, use one gallon of regular liquid bleach in the disinfection process.
  • Use good safety practices such as wearing gloves and eye protection.
  • Remember to check for any electrical problems that may exist in the work area.
  • Identify the location where the bleach will be added into the well.
  • Insure proper mixing by attaching a hose to a nearby faucet and running the water back into the well until you can smell a chlorine odor in the water coming from the hose.
  • Open all outdoor and indoor faucets to pull the chlorinated water through the plumbing.
  • Let the chlorinated water sit in the plumbing for at least six hours and no more than 24 hours. While waiting, check to insure that the well has a proper sanitary seal.  
  • After the wait period is over, begin flushing the chlorine out of the system by opening an outside faucet.
  • Direct the discharge water away from lakes, streams or any areas that drain into your septic tank.
  • Continue flushing until the chlorine odor can no longer be detected.
  • Wait a minimum of 7 to 10 days before collecting a water sample for testing purposes.

Remember, if you have any questions about an individual residential well, you can contact a certified well driller or your local DHEC representative.