Bacteria: Sources, Types, Impact on Water Quality - A General Overview
Water Quality/Impaired Waters , 2008

Minnesota Pollution Control Agency

Countless numbers of bacteria, viruses, and other microorganisms exist in the environment – land and water – and also in the bodies of humans and animals. Most are beneficial, serving as food for larger organisms, and playing critical roles in biogeochemical cycles such as organic matter decomposition, fixation of nitrogen, and digestion of food. However, about 10 percent are harmful. Known as pathogens, if ingested by humans, they can release toxins causing sickness or even death. Symptoms of waterborne diseases may include gastrointestinal illnesses such as severe diarrhea, nausea, and possibly jaundice as well as headaches and fatigue. It is important to note, however, that these symptoms are not associated only with disease-causing organisms in drinking water. They may also be caused by a number of other factors. In addition, not all people will be affected to the same degree; young children and the elderly are usually more susceptible.