Expert Views

Coliform Bacteria and Drinking Water by Jack West

What are coliform bacteria?

Coliform bacteria are commonly found in soil, on vegetation, and in surface waters. They also live in the intestines of warm-blooded animals and humans. Some coliform bacteria strains can survive in soil and water for long periods of time. Coliform bacteria will not likely cause illness in most people; however, because coliform bacteria are most commonly associated with sewage or surface waters, the presence of coliform bacteria in drinking water indicates that other disease-causing organisms (pathogens) may be present in the water source or its distribution system.

There are three different groups of coliform bacteria, and each has a different level of health risk:

  1. Total coliform bacteria are commonly found in the environment and are generally harmless. If only total coliform bacteria are detected in drinking water, the source is probably environmental, and fecal contamination is not likely. If environmental contamination can enter the system, however, that suggests there may be a way for pathogens to enter the system. Therefore it is important to determine the source and resolve the problem.
  2. Fecal coliform bacteria are a sub-group of the total coliform group. They are found in great quantities in the feces of people and animals. The presence of fecal coliform in a drinking water sample often indicates recent fecal contamination -- meaning that there is a greater risk that pathogens are present than if only total coliform bacteria are detected.
  3. E. coli is a sub-group of the fecal coliform group. Most E. coli are harmless and are also found in great quantities in the feces of people and warm-blooded animals. Some strains, however, may cause illness. Some of these common waterborne illness symptoms include diarrhea, vomiting, headache, and cramps (acute gastrointestinal illness). Populations at highest risk to this ailment are: the very young, the very old, and persons with compromised immune systems. The presence of E. coli in a drinking water sample almost always indicates fecal contamination of the water supply, and so E. coli outbreaks usually receive a lot of media attention. Many food borne outbreaks have been caused by an especially virulent strain of E. coli known as E. coli 0157:H7 which can cause serious illness or death.

E. coli Regulations

The current Federal drinking water regulations for public water supplies (EPA) and bottled water (FDA) are undergoing revisions (Ground Water Rule amendments) for the improved detection and prevention of E. coli contamination of both types of drinking water. When fully implemented, the respective E. coli maximum contaminant levels will be: no more than 5% positive E. coli samples from a public water supply which samples more than 40 times per month (same as current EPA standard); zero positive E. coli samples from a finished bottled water product or its source water (a zero tolerance FDA Standard of Quality).

A violation of the E. coli standard for a public water supply calls for correction of the deficiency and notification of the public and the responsible state authorities. A bottled water producer in violation of the E. coli standard will be prohibited from releasing the finished product into the marketplace or using a contaminated source until the violation is corrected. In addition to public notification, contaminated bottled water product recall from the field and product destruction will be required.

Jack West is the Chairman of the Board of Trustees of the Drinking Water Research Foundation (DWRF) in Alexandria, Virginia. With over 30 years of experience in the bottled water industry, he is now an advisor on drinking water quality issues.

References:
CDC: "A Survey of the Quality of Water Drawn from Domestic Wells in Nine Midwestern States" 9/2004
City of Lacey, MI: "Coliform Bacteria and Drinking Water Fact Sheet"
Michigan Dept of Environmental Quality Water Division "Coliform Bacteria and Well Water Sampling Fact Sheet"
Federal Register: FDA Proposed Amendments to CFR 21 parts 129 and 165; Vol 73, No. 181, pg 53775, September 17, 2008
Federal Register: EPA Ground Water Rule; Vol 71, pg 65574, November 8, 2006