Drinking coliform bacteria is potentially fatal for infants, the elderly and individuals who are ill, according to Purdue University Cooperative Extension Service. Fatalities are due to acute intestinal infections caused by high levels of coliform bacteria.
Health concerns arise when the coliform bacteria levels in water are greater than 1 per 100 milliliter of water, according to Purdue University Cooperative Extension Service. Individuals who are not infants, elderly or ill usually experience no more than discomfort due to the acute intestinal infections.
Most strains of coliform bacteria do not cause disease, according to the New York State Department of Health. Some rare strains of coliform bacteria, namely E.coli strain 0157:H7, can cause dangerous illness. Humans generally contract illness from this strain due to eating undercooked hamburger rather than drinking contaminated water.
Coliform bacteria live in vegetation, soil and the gastrointestinal tract of animals, according to ExtoxNet. Water can become contaminated by coliform bacteria when waste, dirt or sewage enters the water source. Many individuals grow immune to bacteria in their own water, while visitors have not built an immunity and may experience gastrointestinal problems from drinking the contaminated water.
The only reliable way to know if water is safe is to test for bacteria, according to the New York State Department of Health.