What is Coliform Bacteria?


What is Coliform Bacteria?

Coliform bacteria are present in the environment and feces of all warm-blooded animals and humans. Coliform bacteria are unlikely to cause illness. However, their presence in drinking water indicates that disease-causing organisms (pathogens) could be in the water system. Most pathogens that can contaminate water supplies come from the feces of humans or animals. Testing drinking water for all possible pathogens is complex, time-consuming, and expensive. It is easy and inexpensive to test for coliform bacteria. If testing detects coliform bacteria in a water sample,water systems search for the source of contamination and restore safe drinking water.

What are the different types of coliform bacteria?

There are three groups of coliform bacteria. Each is an indicator of drinking water quality

and each has a different level of risk. Total coliform is a large collection of different kinds of bacteria. Fecal coliform are types of total coliform that exist in feces. E. coli is a subgroup of fecal coliform. Labs test drinking water samples for total coliform. If total coliform is present, the lab also tests the sample for fecal coliform or E. coli, depending on the lab testing method.


Total coliform bacteria are common in the environment (soil or vegetation) and are generally harmless. If a lab detects only total coliform bacteria in drinking water, the source is probably environmental and fecal contamination is unlikely. However, if environmental contamination can enter the system, pathogens could get in too. It is important to find and resolve the source of the contamination.

Fecal coliform bacteria are a subgroup of total coliform bacteria. They exist in the intestines and feces of people and animals. The presence of fecal coliform in a drinking water sample often indicates recent fecal contamination. That means there is a greater risk that pathogens are present.

E. Coli is a subgroup of the fecal coliform group. Most E. coli bacteria are harmless and exist in the intestines of people and warm-blooded animals. However, some strains can cause illness. The presence of E. coli in a drinking water sample usually indicates recent fecal contamination. That means there is a greater risk that pathogens are present.

What if coliform bacteria are found in my water?

When coliform bacteria are found, water systems investigate to find out how the contamination got into the water. They collect additional water samples and often inspect the entire system. Collecting additional samples helps determine whether an actual problem exists. If the lab detects bacteria in any of the additional samples, the initial findings are “confirmed.”

What if total coliform bacteria are confirmed in my water?

If a lab confirms total coliform bacteria in your drinking water, your water system will investigate to find out how the contamination got into the water. After identifying the source of contamination, the system can usually resolve the problem with system repairs, flushing, and adding chlorine for a short period.

What if fecal coliform bacteria or E. coli are confirmed in my water?

Confirmation of fecal coliform bacteria or E. coli in a water system indicates recent fecal contamination, which may pose an immediate health risk to anyone who consumes the water. The water system will issue a “health advisory” within 24 hours to alert all water users of a health risk associated with the water supply. The advisory usually recommends using boiled or bottled water for drinking, preparing food, and brushing teeth. It also outlines the steps underway to correct the problem and explains when the system expects to resolve the problem. The health advisory will remain in effect until the situation is resolved and the water is safe to drink.

Whole House Ultraviolet Disinfection System for Bacteria and Viruses


Our Ultra-violet (UV) light is 99.9% effective against disease causing micro-organisms such as E. coli. By exposing contaminated water to high intensity UV light disease causing micro-organisms are rendered harmless.

Filtercon offers Whole House Ultraviolet Systems, as well as small units for under the counter ultraviolet sink faucets.

Ultraviolet disinfection systems are safe, proven to be effective , and have been used worldwide for many years.

Ultraviolet units can be installed alone, or together with a whole house filter, or with an under the sink filtration unit.

Call FILTERCON for more information (800) 550-1995

Article by the Department of Health Washington State
Original Link: http://www.doh.wa.gov/Portals/1/Documents/Pubs/331-181.pdf

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