Fecal coliform
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A fecal coliform (British: faecal coliform) is a
Fecal bacteria as indicator of water quality
Background
In general, increased levels of fecal coliforms provide a warning of failure in water treatment, a break in the integrity of the distribution system, possible contamination with pathogens. When levels are high there may be an elevated risk of waterborne gastroenteritis. Tests for the bacteria are cheap, reliable and rapid (1-day incubation).
Potential sources of bacteria in water
The presence of fecal coliform in
Human sewage
Failing home
Animals
Pets, especially
, and rivers.Agriculture
Agricultural practices such as allowing livestock to graze near water bodies, spreading manure as fertilizer on fields during wet periods, using sewage sludge biosolids and allowing livestock watering in streams can all contribute to fecal coliform contamination.
Problems resulting from fecal contamination of water
Human health hazards
Large quantities of fecal coliform bacteria in water are not harmful according to some authorities, but may indicate a higher risk of
Effects on the environment
Untreated
Removal and treatment
Fecal coliform, like other bacteria, can usually be inhibited in growth by boiling water, treating with chlorine, or UV disinfection. Washing thoroughly with soap after contact with contaminated water can also help prevent infections. Gloves should always be worn when testing for fecal coliform. Municipalities that maintain a public water supply will typically monitor and treat for fecal coliforms. It can also be removed by iodine.
Testing
Public health risk monitoring
In waters of the U.S., Canada and other countries, water quality is monitored to protect the health of the general public. Bacteria contamination is one monitored pollutant. In the U.S., fecal coliform testing is one of the nine tests of water quality that form the overall water-quality rating in a process used by U.S. EPA. The fecal coliform assay should only be used to assess the presence of fecal matter in situations where fecal coliforms of non-fecal origin are not commonly encountered.[1] EPA has approved a number of different methods to analyze samples for bacteria.[4]
Analysis
Bacteria reproduce rapidly if conditions are right for growth. Most bacteria grow best in dark, warm, moist environments with food. When grown on solid media, some bacteria form colonies as they multiply which may grow large enough to be seen. By growing and counting colonies of fecal coliform bacteria from a sample of water, the amount of bacteria originally present can be determined.
Newer methods for coliform detection are based on specific enzyme substrates as indicators of coliforms. These assays make use of a sugar linked to a dye which, when acted on by the enzyme
More recently, the chemistry behind enzymatic detection compounds has been updated so that the indicating component is redox active, as opposed to the more usual chromogenic format, allowing fecal indicator bacteria such as E. coli and E. faecalis to be detected electrochemically without any sample pre-treatment. Since the colour of the detection compound is of no consequence, this allows detection in deeply coloured matrices.[5]
US EPA testing requirements
In 1989 the
See also
References
- ^ ISSN 1558-7460.
- ISBN 0 419 22320 7(Hbk) 0 419 21730 4 (Pbk)
- ^ Fresno County Department of Public Health. Fresno, CA (2009)."E. coli or Fecal Coliform Bacteria Contamination in Your Water Supply." Archived 2011-07-18 at the Wayback Machine Notice distributed to private well owners.
- ^ U.S. Environmental Protection Agency (EPA). Washington, DC (2008). "Analytical Methods Approved for Drinking Water Compliance Monitoring under the Total Coliform Rule." June 2008.
- PMID 27364994.
- ^ EPA (1989-06-29). "Drinking Water; National Primary Drinking Water Regulations; Total Coliforms (Including Fecal Coliforms and E. Coli)." Final rule. Federal Register, 54 FR 27544
- ^ EPA (2013-02-13). "National Primary Drinking Water Regulations: Revisions to the Total Coliform Rule." 78 FR 10269
- ^ EPA (2014-02-26). "National Primary Drinking Water Regulations: Minor Corrections to the Revisions to the Total Coliform Rule." 79 FR 10665