Small Systems Water Treatment Plant Operator Program Manual

SMALL
SYSTEMS
WATER
SOURCES
& CHARACTERISTICSC
& C
The Guidelines for Canadian Drinking Water Quality state that no 100mL test
should show the presence of faecal coliforms.
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If you receive a positive result for faecal coliform, after you immediately check your
disinfection system, you must contact the EHO and follow instructions.
Usually, a second test will be taken to confirm the first, and again while you wait for
the results, you need to assess your system.
3.5.2.3 Escherichia coli (E. coli)
E. coli is a specific type of faecal coliform that is often used as a benchmark test for
pathogenicity of faecal coliforms. It is important to note that not all E. coli are
harmful. In fact there are over 25,000 strains (bacterial varieties), but only 150 might
make you a bit sick and only one strain, O157:H7, will make you truly ill.
The O157:H7 E. coli strain causes what is known as “Hamburger Disease” because it
is more often associated with improperly cooked meat.
E. coli tests can be conducted as a standard presence/absence test. It is preferred to the
faecal coliform count because it can be done in 24 hours, compared to 48.
If you have a positive result for E. coli, the actions are the same as for faecal coliform.
3.5.3 PROTOZOA
Protozoa are small microorganisms about 4 to 40 microns is size, that are more similar
to animals than bacteria. They are larger than bacteria, their eggs have a hard shell,
and are resistant to chlorine.
Two of the most common protozoa related to health problems from drinking water are
Cryptosporidium and Giardia. When people get ill from these organisms, they do not
build immunity as they would from a viral infection. Therefore, they can get ill over
and over again.
Giardia (gee-ar-dee-a) comes from warm-blooded mammals such as beaver, muskrat,
caribou, dogs, and man. Sometimes called "beaver fever", its symptoms are like the
flu.
Cryptosporidium is more serious than Giardia. The diarrhoea caused by this organism
can be compared to that caused by cholera and can cause death. Children, Elders, and
people with reduced immune systems are most susceptible.
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