Total Coliform Rule

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Drinking Water Rules
Total Coliforms

Published in 1989, the Total Coliform Rule requires all public water systems to monitor for the presence of coliforms within the distribution system. There are thousands dangerous microbes that may turn up in drinking water, but testing for each of these would be difficult and expensive. Instead, analytical labs test for coliform bacteria as an indicator of water safety. Because coliforms are common in water, easy to identify, and are affected by the same environmental stresses and treatment as many pathogens, the EPA considers their presence in water to be an indicator that dangerous pathogens may also be present.

The coliforms are a broad class of bacteria which live in the digestive tracts of humans and many animals. The presence of coliform bacteria in tap water suggests a problem in either the water treatment system or the distribution system. Although many types of coliform bacteria are harmless, some can cause intestinal discomfort for healthy adults, and more serious problems for the very young, the elderly, or the immuno-compromised.

The Total Coliform Rule sets both health goals (MCLGs) and legally enforceable limits (MCLs) for coliforms in drinking water. The rule also details the type and frequency of testing that must be done. Since there have been waterborne disease outbreaks caused by very low levels of coliforms, the MCLG for total coliforms is set at zero, on the assumption that any exposure presents a health risk.

The MCL for total coliforms is 5%, meaning that if more than five percent of the samples taken each month contain coliforms, water system operators must report this violation to the state and the public.

Many municipal and private water suppliers trust their analytical testing to Neilson Research Corporation. Our lab is unsurpassed in the production of unquestionable data, sample handling, and customer service. Let our staff help with any questions you have regarding coliform bacteria, E. coli, or monitoring compliance.

Contaminant	MCLG	MCL	Potential Health Effects	Sources of Contaminant
Total Coliforms including Fecal coliforms and E. coli	zero	5.0%	Used to indicate presence of potentially harmful bacteria	Coliforms are naturally present in the environment. Fecal coliforms and E. coli come from human and animal waste.

To learn more about the MCLs for all of the EPA regulated contaminants, see
http://www.epa.gov/safewater/disinfection/tcr/pdfs/qrg_tcr_v10.pdf