Water Microbiology for State and Federal Agencies
Total Coliform (Bacteria) Testing for Drinking Water:
Total Coliforms are indicator organisms used to detect bacterial contamination in drinking water. Their presence indicates that a pathway for contamination exists and organisms that cause disease may be present, even though total coliforms themselves typically do not cause disease in healthy individuals. The most common symptoms caused by disease-causing organisms in drinking water are nausea, vomiting and diarrhea. Total coliforms are found naturally in soil, surface water, plant material, and insects; however, one species of total coliform (E. coli) are found in the feces of warm blooded animals. Total coliforms are not naturally found in well water or groundwater. Wells should be tested yearly if there is a history of total-coliform-absent (bacteriologically safe) results or more frequently if there is a change in the water quality because of color, taste or odor.
E. coli Testing for Drinking Water:
E. coli is an indicator organism of fecal contamination. The natural habitat for E. coli is the intestinal tract of warm blooded animals. The presence of E.coli in a drinking water sample is an indication of fecal contamination of the water supply. E. coli is a subset of total coliform, so if there is no total coliform present in the water sample, there is no E. coli.
Cryptosporidium and Giardia Testing:
These are parasites that must be swallowed to cause disease. The organisms are spread by the fecal-oral route. The illness caused by Cryptosporidium is characterized by watery diarrhea and abdominal cramps. The illness caused by Giardia is characterized by nausea and fatigue, followed by watery diarrhea that can last more than 10 days. These organisms are measured in source waters for drinking water systems that use surface water.
Iron bacteria are naturally present in surface water and soil. Iron bacteria do not cause illness, but are considered nuisance bacteria. They can produce orange/brown slime that builds up inside well screens, pipes and plumbing fixtures. The presence of odors and/or brown-tinted water and/or brown-tinted staining on fixtures is an indication of iron bacteria. The treatment for iron bacteria is disinfecting the well.
Sulfate Reducing Bacteria:
Like iron bacteria, sulfate reducing bacteria do not cause illness, but are nuisance bacteria. They are found in soil and surface water. Sulfate reducing bacteria can lead to corrosion in well casings, pipes, cement and other materials and can produce an unpleasant odor (rotten egg) in water. The treatment for sulfate reducing bacteria is disinfecting the well.
Helicobacter pylori are a bacteria species that cause peptic ulcers in humans. Currently, the human and animal (warm-blooded) stomach and intestinal tract is the only proven domain for this pathogen. However, research shows evidence that H. pylori also exists in the environment (surface & ground water, manure, vegetables, etc.) and could be transmitted to humans who incidentally consume the contaminants.
Heterotrophic Plate Count:
This test estimates the number of live bacteria that are able to grow on a specific media at a specific temperature and incubation period. This test measures changes during water treatment and in a distribution system. This test is also one of the tests used to measure the disinfection efficiency of whirlpools, pools and spas.
Swimming Beach Testing:
Swimming beaches should be tested for water quality before the swimming seasons begins, to get a baseline of contamination resulting from natural wildlife or run-off, and each week thereafter until the season ends. Beaches may be regulated by local ordinances or local health standards. The standards developed for the Great Lakes in Wisconsin and may be used for inland beaches are:
Total Coliform (Swimming Pool) testing:
This test is one of the tests used to measure the disinfection efficiency of swimming pools and whirlpools.
Pseudomonas aeruginosa is considered an opportunistic pathogen and may cause skin rashes when appropriate levels of disinfection are not maintained in whirlpools and pools. This test is one of the tests used to measure the disinfection efficiency in whirlpools, pools and spas.
Surface Water Testing:
Various tests are used to investigate recreational water, stream or lake pollution, and wastewater treatment systems. The following are tests available for surface water testing:
Video - Beach Water Collection for E. Coli Testing
High-bandwidth video (2 Mbps)
Low-bandwidth video (81 Kbps)
The video was produced by the Wisconsin State Laboratory of Hygiene, with funding provided by the State Lab of Hygiene, the Wisconsin Department of Natural Resources and the Wisconsin Department of Health and Family Services.
Bacteroides spp. is present in human and animal fecal material. They are strict anaerobes so they do not grow in the environment. The presence of Bacteroides spp. indicates fecal contamination. A series of DNA-based tests can be used to determine whether fecal contamination is present in a source water (surface or well water), and whether that contamination may be of human or bovine (cow) origin.
Sorbitol-ferementing Bifidobacteria are present in human fecal material. They are strict anaerobes, so they do not grow in the environment, making them excellent indicators of recent human fecal contamination.
Rhodococcus coprophilis is found in association with manure of domesticated grazing animals like cows, sheep, horses, goats, etc. To date it has never been isolated from human feces. The presence of Rhodococcus coprophilis indicates grazing animal contamination.
Male-specific coliphage genotypes
Male-specific coliphages are viruses that infect coliforms. As such, their presence indicates the presence of fecal contamination in a water source. These viruses can be enumerated and genotyped. Group I and IV coliphages are associated with non-human fecal sources, while Group II and III are associated with human fecal sources.