The U. S. Environmental Protection Agency (EPA) requires public water systems to regularly test water for total coliform bacteria and E. coli. Safe drinking water does not have E. coli or other pathogens in it.
If you have a private well
Here are some recommendations on how to prevent and address coliform bacteria contamination:
Prevent Contamination
- Protect Your Well by constructing it in a safe spot.
- Regularly inspect your well for damage. Contact a Licensed Well Contractor if you find any damage.
- Test your well water every year for coliform bacteria. You are responsible for keeping your well water safe and testing it as needed. All well testing should be done through an accredited laboratory. Contact a Minnesota Department of Health (MDH) accredited laboratory to get a sample container and instructions on how to submit a sample. You can also contact your county to see if they have any programs to make testing your water easier.
- Disinfect your well with a chlorine solution if floodwaters come within 50 feet of your well; your water changes in taste, appearance, or odor; or your well is opened for servicing. Follow these steps for Well Disinfection or hire a Licensed Well Contractor.
- Conduct routine maintenance of potential sources of contamination, such as household septic systems.
Address Contamination
If coliform bacteria are detected in your water, follow these steps:
- Stop using the water for drinking and preparing food, unless you boil it at a full rolling boil for a full minute before using it. You can also use bottled water or water from a known safe alternative source.
- Disinfect your well with a chlorine solution, using the same Well Disinfection steps as above.
- Test your well water again after disinfection to confirm there are no coliform bacteria.
- You can use the water again, without boiling, once the well has been disinfected and the water no longer tests positive for coliform bacteria. Contact MDH (800-383-9808 or health.wells@state.mn.us) with questions.
If you are on a public water system
Your public water system is regularly tested for coliform bacteria. The system will issue a public notice within 24 hours if it detects E. coli. The public notice will tell you what you should do to stay safe.
You can find the coliform bacteria test results for the system serving where you live by reading the system's Water Quality Report (also known as a Consumer Confidence Report [CCR]). You can call your public water system to get a paper copy of your CCR, or you may be able to find it online at Find Your Local CCR. You can find the coliform bacteria test results for the systems serving places other than where you live by contacting the water system.
