Division of Environmental and Community Health

Maine Center for Disease Control & Prevention

A Division of the Maine Department of Health and Human Services

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Frequently Asked Questions About Coliform Bacteria and Boil Water Orders

Coliform Bacteria and Boil Water Orders – FAQ


What are coliform bacteria?

Coliform Bacteria are a class of rod-shaped bacteria that can utilize lactose (milk, sugar) as a sole source of food. Coliform bacteria are found essentially everywhere, in soil, lakes, streams and rivers. Generally, coliform bacteria do not cause disease. The presence of coliform bacteria is used as an indication that other disease causing organisms may be present in drinking water.


What are fecal coliforms?

Fecal coliforms are coliform bacteria that will grow at 44° C (106° F). These bacteria are also commonly found in animal and human waste. We use the presence of fecal coliforms as a possible indication of human or animal waste contamination in drinking water. Generally, these bacteria do not cause disease. However, their presence indicates a possible waste contamination problem. E. coli is a fecal coliform bacteria.


Why do I have to boil my water?

A "Boil Water Order" is issued as a preventative measure. We issue a boil order if there is a possibility of contamination in the drinking water system. Contamination may be due to equipment failure, leaking pipes in the system, or insufficient disinfectant in the water supply.


How long should I boil the water?

To ensure any microbial pathogens are rendered harmless, water should be brought to a rolling boil and remain so for at least one minute. This is for any water you are going to consume for drinking, washing vegetables, brushing teeth, or making ice.

You should follow the boil water order until your water supplier advises it is safe to stop.


What about cooking and washing?

If you are going to boil the water while cooking, prior boiling is not necessary. It is not necessary to boil water for washing clothes, dishes, or for bathing.

Guidance for eating establishments during and after a Boil Water Order (PDF)

Guidance for consumers during and after a Boil Water Order (PDF)


What should I do if the water is making me sick?

If you believe your water is making you sick, see your physician right away. Your doctor has the knowledge, expertise, and ability to run lab tests to see if the water is what is making you sick. Symptoms associated with waterborne illness are also associated with food borne illness, or even the common cold. If your physician determines that your drinking water is making you sick, your case should be referred to the Maine Center for Disease Control and Prevention.

Updated 2/10/2023