LaMotte MF 3-0035 - Manual (Page 8)

Interpretation of Results
• Non-fecal coliforms are widely distributed in nature, being found both as
naturally occurring soil organisms, and in the intestines of warm-blooded
animals and humans. Fecal coliforms, such as E. coli, are coliforms found
naturally only in the intestines of warm-blooded animals and humans. The
presence of fecal coliforms is therefore the result of some form of fecal
contamination from either animal or human.
• 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.
• Proper application of the Coliscan MF filtration method will result in accurate
results. Therefore, if the results indicate dangerously contaminated water,
contact your local health department for help in performing an official
assessment of the water quality.
• Water containing E. coli should not be used for drinking water. Contact your
local health department for guidelines regarding E. coli and coliforms in
recreational water.
• Most standard counts are reported as CFU/100mL of water
• Check your state water quality guidelines (see references).
Sample Dilution
• Samples with large coliform concentrations may have to be diluted to bring the
number of colonies into a practical range. The target range should be between
20 and 80 colonies. Below 20 colonies the results will not be significant.
Colonies greater than 80 will be too numerous to count (TNTC).
• Samples that are less than 10 mL will need to be diluted with 10-20 mL of a
sterile diluent before filtering. Samples can be diluted with 1% peptone water
or Butterfield Phosphate Buffer if they are available. Sterile water from a
medical supply company or pharmacy or boiled, cooled tap water is also
acceptable.
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, offseason swimming areas, or
fish and wildlife habitat.
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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
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