LaMotte EZ 3-0034 - Manual (Page 9)

Water Sampling
• The sample is collected while facing upstream to avoid contamination from the
hand holding the bottle. Wearing protective gloves will also decrease the
chance of contamination.
• Be aware of animals, like ducks or geese, which may be upstream from where
the sample was taken because their feces will increase the E. coli and coliform
count temporarily, therefore, the results will not reflect the true nature of the
water quality.
Back ground of Wa ter Testing
In 1972, the U.S. public was concerned about the pollution in our nation’s water.
Congress responded by passing the Federal Water Pollution Control Act
Amendments, also known as, the Clean Water Act of 1972. The goal of the Act was
to protect human health by preventing water pollution. Water pollution comes in
many forms and from many sources. The U.S. Environmental Protection Agency (EPA
or USEPA) manages the water quality standards program, recommends water quality
criteria, and works with states to develop standards for different water use, such as
beach swimming areas, rarely used swimming areas, off season swimming areas, or
fish and wildlife habitat.
2
Water can be contaminated or polluted with disease causing organisms (pathogens).
When people swim in these waters, they can get sick with ear or skin infections,
respiratory infections, or intestinal infections. The pathogens responsible for these
diseases can be bacteria (Cholera), viruses (Hepatitis A), or parasites (Giardia and
Cryptosporidium) that live in the gastrointestinal tract and are shed into the water
through the waste (feces) of warm-blooded animals. However, analyzing for all
possible pathogens is impractical. It is difficult, time consuming, and expensive. The
EPA recommends using indicator organisms, such as fecal bacteria, as indirect
evidence of the possible presence of pathogens in water.
2 The two most important
fecal bacteria indicators are E. coli and Enterococcus. We will discuss the use of E. coli
as it relates to the USEPA standards for water pollution. 2
Escherichia coli (E. coli) is the United States Environmental Protection Agency’s
(USEPA) most commonly recommended indicator of fecal contamination in fresh
waters. It is present in high numbers in the gastrointestinal tracts of warm-blooded
animals (humans, dogs, bears, cows, ducks, geese) and therefore provides a sensitive
measure of fecal pollution. Researchers have found that its presence in water is often
associated with water borne illness outbreaks actually caused by the other pathogens
mentioned above. E. coli do not live long in water so that their presence indicates a
fairly recent contamination event (up to 48 hours).
The current EPA water quality standard for E. coli relates to approximately 8
gastrointestinal illnesses per 1,000 swimmers. This is considered an acceptable level
of disease for people who come in contact with the tested water. If the indicator counts
are measured above the standard acceptable level, then the risk of becoming infected
from that water source is unacceptably high. In the past fecal coliforms were used as
the indicator for water standards with maximum allowable counts of 200 FC (fecal
coliforms) per 100 mL.
2
Coliform bacteria are members of the family Enterobacteriaceae, which are gram
negative, non-spore forming rods that ferment the sugar lactose to produce gas and
acid. E. coli is a genus (Escherichia) and species (coli) in the total coliform group. It is
also a fecal coliform (FC), a smaller subset of total coliforms. Fecal coliforms are
defined as coliforms that can grow at 44.5°C, which is too hot for most of the other
coliforms. Fecal coliforms live in the gastrointestinal tract of warm-blooded animals,
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