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Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Fecal Coliform and E. coli

The persistent presence of fecal coliforms may require emergency disinfection of drinking water

What are coliforms, fecal coliforms and E. coli?

Coliforms are bacteria that live in the intestines of warm-blooded animals (humans, pets, farm animals, and wildlife). Fecal coliform bacteria are a kind of coliform associated with human or animal wastes. Escherichia coli (E. coli) is part of the group of fecal coliforms.

Why do we test for coliforms?

In themselves, coliforms generally do not pose a danger to people or animals, but they indicate the presence of other disease-causing bacteria, such as those that cause typhoid, dysentery, hepatitis A, and cholera. Both coliforms and disease-causing bacteria live in water. But unlike coliforms, disease-causing bacteria generally do not survive long enough in the water, outside the body of animals, to be detected. Sampling and testing for the presence of disease-causing bacteria is therefore difficult; instead, scientists and public health officials consider the presence of coliforms an indicator of disease bacteria in recreational, drinking and flood waters.

How do E. coli and other fecal coliforms get in the water?

Fecal contamination can arise from sources such as combined sewer overflows, leaking septic tanks, sewer malfunctions, contaminated storm drains, animal feedlots, and other sources. During rainfalls, snow melts, or other types of precipitation, E. coli may be washed into creeks, rivers, streams, lakes, or ground water. When these waters are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water.

What precautions should I take if I come into contact with water that might have unsafe levels of E. coli in it?

Skin contact: Testing results after Hurricane Katrina have indicated levels of E. coli in flood waters in the New Orleans area that greatly exceed EPA's recommended levels for contact. Emergency responders and the public should avoid direct contact with standing water when possible. In the event that you come into contact with flood waters, EPA and CDC strongly advise that you apply soap and water to clean exposed areas.

Ingestion: Flood water should not be swallowed and all mouth contact should be minimized and avoided where possible. You should immediately report to health professionals any symptoms that you might have ingested flood water contaminated with bacteria, such as stomach-ache, fever, vomiting and diarrhea. Also, you can become ill if you have an open cut, wound, or abrasion that comes into contact with water contaminated with certain organisms. You may experience fever, redness, and swelling at the site of an open wound, and you should see a doctor right away if possible.

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