Articles & FAQ

Coliform Bacteria

By Mike Temple, GeoWater Services

Total coliform is a group of several species of bacteria with similar characteristics.  They all may be found naturally in the environment; in the soil, in plants and animals. Most coliform bacteria can be found in the intestinal tract of warm-blooded animals.  Some species of coliform bacteria are Klebsiella pneumoniae and Enterobacter aerogenes.  Fecal coliform bacteria are a sub-group of the total coliform group. E. coli is the most well-known species of fecal coliform bacteria.  All fecal coliform are associated directly with warm-blooded animals, including humans.

Total coliform are “indicator” bacteria. Their presence indicates the possible presence of disease-causing organisms; other bacteria, viruses or protozoa, such as Giardia, Salmonella, Cryptosporidium, and Shigella.  These pathogens cause diseases like typhoid fever, cholera, and gastroenteritis.  The presence of fecal coliform bacteria (specifically E. coli) indicates contamination from fecal matter and the more probable presence of pathogens. Safe water contains no coliform (total OR fecal) bacteria.

Testing for all possible pathogens in water is impractical & expensive.  The total coliform test has been designated by the EPA as the standard to determine biological safety of drinking water.  Total coliform have been used for many years to determine the basic quality of drinking water. Coliform bacteria react to the environment & treatment processes in a manner similar to pathogens. Other reasons for choosing coliform as indicator bacteria are they are present in larger numbers, have a longer survival rate in water, and are easier to identify than other pathogens.  Many pathogens are difficult to detect in water. The determination of fecal coliform in water points more to a specific source of contamination, particularly an ISDS, animal feedlot, dog run, etc.

GeoWater Services, LLC, suggests testing annually for coliform bacteria, based upon recommendations from the EPA.  More frequent testing is suggested for wells that have had a bacterial problem in the past.