Health Department - Environmental Health Programs

Well Disinfection

Procedure for Disinfecting Residential Water Wells
and Distribution Systems

Obtain a quart of unscented regular household bleach.

1) Open the top of the well and pour in the measured amount of bleach. Run water from a hose connected to a faucet/spigot furthest away from the well until water has a strong chlorine odor or taste. This process may take 60 minutes or more (perhaps 4 hours or even longer) depending on the depth of the well, the depth of the pump, the length and size of distribution pipes and hoses.

2) Once chlorine is observed from the circulating hose, open "all" outside and inside faucets in "successive" order until the odor of chlorine is detected and then shut off. That means open the faucet smell the chlorine and shut off the faucet. This ensures the chlorine is contacting all surfaces within the plumbing system and well. NOTE: We would suggest opening the hot and cold taps furthest from the source until chlorine is detected. Shut these taps off and in a systematic manner moving back towards the source, open each faucet until chlorine is detected, then close. Don't forget to flush toilets and cycle dishwashers and clothes washers and ice makers.

3) Allow the water to stand in the pipes for 12 to 48 hours. In most cases 12 to 16 hours or overnight is sufficient. NOTE: Water consumption during this time frame is not recommended.

4) At the conclusion of the contact period, open the faucets furthest from the source and make sure the odor of chlorine is still detectable. If this is the case, then open all faucets, outside the home and run water, until the smell or taste of chlorine is gone. Once the smell is gone flush all the inside faucets, toilets, dishwashers and clothes washers shutting off the water at each faucet as the odor leaves. If the smell of chlorine is not present when the tap furthest from the source is opened, repeat steps 1 through 3 and double the amount of bleach added to the well.

5) After 48 hours of normal usage, re-sample the water using the water sample bottle you picked up from the health department. NOTE: The sample should be collected and brought in to the Division of Environmental Health Office within 16 hours.

6) A one time chlorination/disinfection of system may not remedy the problem. Feel free to contact this office for further assistance.

It is important to remember that water is a food, and thus should be produced and transported in a sanitary manner. This means the well must be sealed in such a manner so as to protect it from all sources of contamination.

All construction of the water system must be completed prior to the start of disinfecting!

Recommendations:
1. Have the total coliform run on your water at least twice each year, once in late spring and again in late fall.

2. Have a professional inspect the well once every 5 to 10 years or any time persistent bacteriological problems occur.

3. Keep all records and water reports on the well from the time of drilling to present. These records may prove useful in diagnosing and/or curing problems.

4. NOTES:

A. This is only a bacteriological water test. Other water tests (e.g., chemical and radiological samples) are available through an approved certified laboratory. Contact this office for a list of available laboratories.

B. Private water systems are not covered by Laramie County Regulations and will be inspected only upon owner request as it relates to an unsatisfactory water sample, as a courtesy.

C. Public water systems, both community and non-community are under the regulatory authority of the Environmental Protection Agency (EPA).