Environmental Microbiology

Monitoring Drinking Water

The Environmental Microbiology laboratory monitors drinking water and its sources for the presence of disease-causing organisms. Emerging infectious diseases in the United States and the rest of the world reinforce the need to carefully monitor drinking water. It is not practical to assay for each possible waterborne infectious disease because of the time and cost required to run the numerous tests necessary to detect all possible disease-causing organisms. Scientists have found a more economical method to handle the problem by testing for "surrogate" or "indicator" organisms whose presence indicates that conditions are ripe for transmitting disease-causing organisms. Most of these organisms are common to the intestinal flora in humans and animals.

The ideal indicator organisms must be detectable in all types of water, must be found in sewage and polluted waters when pathogens are present and must be present in greater numbers than the pathogens. The most common organisms meeting these criteria are coliforms. The Environmental Microbiology laboratory uses Colilert (Idexx) test medium to detect coliforms. If coliforms are present, the Colilert test medium can additionally indicate the presence of a specific coliform, E coli, which is the best indicator of fecal contamination. In a normal year, the laboratory staff analyzes about 40,000 drinking water samples

Monitoring Lakes, Rivers & Streams

In addition to drinking water samples, the Environmental Microbiology laboratory works with the KDHE Bureau of Environmental Field Services to analyze surface waters from lakes, rivers, and streams. Public water supplies draw their water from both surface and subsurface waters so it is important that we keep these waters safe. Laboratory staff analyze surface water for E coli so that the number of organisms in the raw water can be estimated by Most Probable Number (MPN). This information helps identify water sources that are safe for use by public water systems. In a normal year, the Environmental Microbiology laboratory will analyze over 4,000 samples of surface water.


For information on drinking water regulations, statutes, and compliance, see the website for the KDHE Public Water Supply Section of the Bureau of Water.

Private Wells

The Environmental Microbiology laboratory does not test private wells. The Environmental Microbiology laboratory only tests water for public water suppliers. Individuals who want their water tested should use the Environmental Laboratory Accreditation page to contact certified water testing labs. Learn more about the testing of private water wells.

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