Drinking coliform-contaminated water may cause abdominal cramping, diarrhea, fever and other flu-like and gastrointestinal upset symptoms, according to the Pennsylvania State College of Agriculture. However, drinking water with coliform bacteria does not always lead to illness.
Coliform bacteria are considered indicator organisms in that they alert testers to the possible presence of disease-causing bacteria in the water source, explains the Pennsylvania State College of Agriculture. The presence of the coliform bacteria suggests the existence of a path between the water supply and the bacteria source. Other types of disease-causing bacteria may use the same pathway to the water supply.
The three groups of coliform bacteria include total coliform, fecal coliform and E. Coli, advises the Washington State Department of Health. Total coliform bacteria are usually harmless and are found in the environment, including soil and vegetation. When total coliform bacteria alone are discovered in a water supply, the cause is typically environmental.
Fecal coliform bacteria is a subgroup of total coliform bacteria, notes the Washington State Department of Health. When testing shows fecal coliform bacteria in the water, the results often mean that the water was recently contaminated with fecal matter, leading to a greater risk of the presence of pathogens. A subgroup of fecal coliform bacteria, E. Coli bacteria are found in the intestines of warm blooded animals, including humans. Generally harmless, some strains of E. Coli can cause illness.