Science of Water : Concepts and Applications

276 The Science of Water: Concepts and Applications
human or animal wastes. The number of fecal coliform bacteria present is a good indicator of the
amount of pollution present in the water.
USEPA’s 816-F-01-035, November 2001 Total Coliform Rule specifi es the following:
1. The purpose of the Total Coliform Rule is to improve public health protection by reducing
fecal pathogens to minimal levels through control of total coliform bacteria, including
fecal coliforms and Escherichia coli (E. coli).
2. Establishes a maximum contaminant level (MCL) based on the presence or absence of
total coliforms, modifi es monitoring requirements including testing for fecal coliforms or
E. coli, requires use of a sample siting plan, and also requires sanitary surveys for systems
collecting fewer than fi ve samples per month.
3. The Total Coliform Rule applies to all public water systems.
4. Implementation of the Total Coliform Rule has resulted in reduction in the risk of illness
from disease-causing organisms associated with sewage or animal wastes. Disease
symptoms may include diarrhea, cramps, nausea, and possibly jaundice, and associated
headaches and fatigue.
Fecal Coliforms: General Information
As mentioned, fecal coliforms are used as indicators of possible sewage contamination because they
are commonly found in human and animal feces. Although they are not generally harmful themselves,
they indicate the possible presence of pathogenic (disease-causing) bacteria and protozoans
that also live in human and animal digestive systems. Their presence in streams suggests that pathogenic
microorganisms might also be present, and that swimming in or eating shellfi sh from the
waters might present a health risk. Since testing directly for the presence of a large variety of pathogens
is diffi cult, time-consuming, and expensive, water is usually tested for coliforms and fecal
streptococci instead. Sources of fecal contamination in surface waters include wastewater treatment
plants, on-site septic systems, domestic and wild animal manure, and storm runoff.
In addition to the possible health risks associated with the presence of elevated levels of fecal
bacteria, they can also cause cloudy water, unpleasant odors, and an increased oxygen demand.
√ Note: In addition to the most commonly tested fecal bacteria indicators, total coliforms, fecal
coliforms, and E. coli, fecal streptococci and enterococci are also commonly used as bacteria
indicators. The focus of this presentation is on total coliforms and fecal coliforms.
Fecal Coliforms
Fecal coliforms are widespread in nature. All members of the total coliform group can occur in
human feces, but some can also be present in animal manure, soil, and submerged wood, and in
other places outside the human body. The usefulness of total coliforms as an indicator of fecal contamination
depends on the extent to which the bacterial species found are fecal and human in origin.
For recreational waters, total coliforms are no longer recommended as an indicator. For drinking
water, total coliforms are still the standard test, because their presence indicates contamination of
a water supply by an outside source.
Fecal coliforms, a subset of total coliform bacteria, are more fecal-specifi c in origin. However,
even this group contains a genus, Klebsiella, with species that are not necessarily fecal in origin.
Klebsiella are commonly associated with textile and pulp and paper mill wastes. If these sources
discharge to a local stream, consideration should be given to monitoring more fecal and humanspecifi
c bacteria. For recreational waters, this group was the primary bacterial indicator until relatively
recently, when the USEPA began recommending E. coli and enterococci as better indicators of health
risk from water contact. Fecal coliforms are still being used in many states as indicator bacteria.
Sampling and Equipment Considerations
Under the EPA’s Total Coliform Rule, sampling requirements are specifi ed as follows: