Coliforms consist of a related group of bacteria species (see table below)
Two Distinct Sources:
• Human and Animal waste (fecal in origin)- septic systems, sewage, animal yards, etc.
• Within the environment ("vegetative")- soil, vegetation, sediment, insects etc.
• Coliforms are "indicator" organisms associated with bacteriologically polluted water.
• Their presence in finished water is indicative of contamination & is not tolerated.
• Extensively studied - their presence may be associated with disease causing organisms.
• Coliform testing does not indicate the presence of specific chemical contaminants
such as pesticides, metals, solvents, gasoline, nitrates, etc.
• Total Coliform Test-theoretically indicates the presence of all coliform group
bacteria, both vegetative and fecal in origin
• E. coli - a coliform species found in the intestinal tract of warm-blooded animals.
- its presence can be indicative of fresh pollution from human or animal waste
- though normally benign, some E. coli strains may be deadly (0157:H7)
• Fecal Coliform-those that ferment lactose & produce gas at 44.5 +/-0.20C within 24
+/- 2 hours
• Consist of various genera and species of coliforms that are specifically associated
with human or animal waste.
- includes E. coli as well as others
- Fecal Coliform testing can help pinpoint the source of pollution in an aquifer
or watershed and is used to monitor the disinfection of sanitary waste water before discharge.
• Total Coliforms:
Escherichia, Enterobacter, Klebsiella, Citrobacter
• Fecal Coliforms:
Escherichia, Klebsiella, Citrobacter (60% to 90% of total coliforms are fecal coliforms) 90%+ of fecal coliforms are Escherichia (usually E. coli)
1. American Public Health Association. Standard Methods for the Examination of
Water and Wastewater, 18th Edition, 1992. Table 9225:I, p. 9-66.
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