How To

A Guide for How to Chlorinate a Well and How to Properly Take a Water Sample

A Guide to Chlorinating Your Well

A Guide to Chlorinating Your Well

This is a guide to chlorinating your well and should be viewed as such

It may take more than one chlorination to eliminate a bacteriological contaminant from a well. If the well has failed more than 3 times, consider increasing the concentration of chlorine added to the well, increasing the time mixing the chlorine and increasing the time the water is run off. For further assistance contact your local well drilling company, or your local health department.

Provide a supply of water for drinking and cooking purposes by boiling water for at least 5 minutes or purchase bottle drinking water.


Household bleach (sodium hypochlorite), such as liquid / granular Clorox or a more potent product is granular chlorine (calcium hypochlorite) available at any pool supply store.


CAUTION: Do not use the heavily chlorinated water for domestic purposes including bathing, laundering and washing sterling silver until strong chlorine odor disappears. If you have a water treatment system contact the conditioning company before running chlorinated water through conditioner.

Dissolve approx. 1 gallon of Chlorine bleach (Clorox) or 1 pound calcium hypochlorite (granular) into 4 to 5 gallons of warm water. NOTE: use one product or the other, DO NOT MIX bleach and granular chlorine. Remove the well cap and pour the mixture into the well. Run a hose from the house into the well and circulate the water for a minimum of 30 minutes. The longer, the better. This will thoroughly dissolve all of the chlorine if granular products were used and it will mix the chlorine into the body of the well. Be sure to rinse the walls and plumbing of the well. After this mixing period is over, go into the house and draw the chlorinated water through the entire plumbing system for proper disinfection. All cold water faucets will need to be opened, outside, inside and the tap at the base of pressure tank allowing the water to run until there is a strong odor of chlorine. Then turn the faucets off. Secure the well cap. The system should remain undisturbed for 24 hours the less water used in the house during this period, the more effective the chlorination. Be sure to bypass any water treatment equipment you may have at the property and do not draw the chlorinated water into the hot water heater. Chlorinate only the cold water lines.


After the chlorinated water has been in the system for 24 hours, attach a garden hose to an outside tap and run the water until the chlorine odor has disappeared. DO NOT run this water into septic system or into any direct water-way. It may take several days to complete the runoff process. Be sure to give the well pump a rest periodically, run the water at your own discretion based on your knowledge of the well pump’s history of performance. Ideally, it is recommended that the water be run for several hours, then shut off for a while, then run again, etc. Continue to use bottled or treated supply water for cooking and drinking. Do not use water for cooking or drinking until water has tested negative for bacteria.


After the outside tap has been running for 24 hours rid the inside of the house of chlorine. Turn on cold water taps inside the house and run for 3-5 minutes each until the water runs clear and the strong odor of chlorine dissipates. The water may be cloudy and discolored, this is normal. Over the next few days it may be necessary to run each tap for several minutes allowing it to clear up and the chlorine smell to dissipate before using the water.


Test the well for chlorine with a chlorine test kit or one provided by C.E.L. Inc. Follow the directions provided. Turn the water off for 1 hour and then test the well for chlorine. If no chlorine is detected in the well water, call C.E.L. Inc. to reschedule your test.

How to Collect A Water Sample