Environmental Engineering Reference
In-Depth Information
• Improperly treated wastewater from municipal systems, septic sys-
tems, or combined sewer overflows
• Runoff from animal stockyards, pastures, and rangeland
• Inadequately captured wastes from human activities such as con-
struction or camping
Fecal coliforms generally do not pose a danger to people or animals. Where
fecal coliforms are present, however, disease-causing bacteria are usually
also present. Unlike fecal coliforms, disease-causing bacteria generally do not
survive outside the body of animals long enough in the water to be detected.
This makes their direct monitoring difficult. Drinking water practitioners
and public health officials consider the presence of fecal coliform an indica-
tor of disease bacteria in the water. The presence of fecal coliforms tends to
affect humans more than it does aquatic creatures, though not exclusively.
Bacteria associated with fecal coliforms can cause significant disease in
humans, such as diarrhea, dysentery, cholera, and typhoid fever. Some of these
bacteria can also cause infection in open wounds. Untreated fecal material that
contains fecal coliforms adds excess organic material to the water; the decay
of this material depletes oxygen in the water, which may kill fish and other
aquatic life. Reduction of fecal coliforms in wastewater may require the use
of chlorine and other disinfectant chemicals; such materials may kill bacteria
essential to the proper balance of the aquatic environment, endangering the
survival of species dependent on those bacteria. Higher levels of fecal coliform
require higher levels of chlorine, further threatening those aquatic organisms.
Total Coliform Rule
The Total Coliform Rule (40 CFR 141.21) is the part of the Safe Drinking
Water Act that addresses detection and removal of bacterial contamination
in drinking water. The Total Coliform Rule applies to every public water
system. Each public water system must take at least one coliform sample
every year and submit the results of that sample to the State Drinking Water
Program for compliance purposes.
Fecal Coliform Testing Procedures
Extensive research has been conducted and is ongoing in an attempt to com-
pare the presence and the significance of specific organisms in water to the tra-
ditional coliform group and waterborne diseases, with the goal of pinpointing
the best indicator of contamination in water. The search continues for a quick,
economic, reliable determination for possible use in routine examination, or
at least during outbreaks of the waterborne diseases. Federal regulations cite
two approved methods for the determination of fecal coliform in water: (1) the
multiple-tube fermentation (MTF) technique for members of the coliform group,
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