The Clark County Combined Health District advises those with water wells at their residence who have experienced flooding that they are at risk of drinking contaminated water.  The risk is greater if the water crested over the top of the well. All surface water is considered to be contaminated with micro-organisms that could cause illness.

During flooding, surface water may enter the well casing and force flood water into the geologic formations that provide the water supply. Water wells that have experienced flooding will require disinfection after the flooding has receded. 

Disinfection consists of pumping contaminated water out and adding the correct amount of a solution of chlorine bleach and vinegar.   After the solution is recirculated, the well is pumped until the disinfection solution is removed.   The Clark County Combined Health District has placed instructions for decontamination of water wells after a flood on the Health District web site:, and is mailing an advisory to residents in areas known to flood.

After water wells have been disinfected, the Health District recommends the water is tested for E Coli and coliform bacteria to determine if the disinfection was effective.  Residents may collect samples for testing and submit them to the Health District.   Sterile sample collection bottles and instructions are available at the Clark County Combined Health District: 529 East Home Road, Springfield, Ohio, 45503. 

For further information or questions, call the Clark County Combined Health District at 937-390-5600 or email at This email address is being protected from spambots. You need JavaScript enabled to view it..