Frequent Questions

4. What indicators does EPA regulate in drinking water, and how do they reflect problems?

IndicatorDescription
Turbidity Turbidity refers to cloudiness of water. Turbidity has no health effects, but can interfere with disinfection and provide a medium for microbial growth. Turbidity may indicate the presence of disease-causing organisms. These organisms include bacteria, viruses, and parasites that can cause symptoms such as nausea, cramps, diarrhea and associated headaches.
Total coliforms Coliforms are bacteria that are naturally present in the environment and used as an indicator that other, potentially harmful, bacteria may be present. Coliforms found in more samples than allowed is a warning of potential problems.
Fecal coliform and Escherichia coli (E. coli) Fecal coliform and E. coli are bacteria whose presence indicates that water may be contaminanted by human or animal wastes. Microbes in these wastes can cause short term effects, such as diarrhea, cramps, nausea, headaches, or other symptoms.  They may pose a special health risk for infants, young children, and people with severely compromised immune systems.
Fecal indicators (Enterococci or coliphage) Fecal indicators are microbes whose presence indicates that the water may be contaminated with human or animal wastes. Coliphage are viruses that infect the bacterium E. coli. Enterococci are bacterial indicators of fecal contamination. Microbes in these wastes can cause short-term health effects, such as diarrhea, cramps, nausea, headaches, or other symptoms. They may pose a special health risk for infants, young children, some of the elderly, and people with severely compromised immune systems.
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