Health
Effects & Standards for Microbiological Contaminants
1. Surface Water Treatment Technique Microbiological
Contaminants
The
United States Environmental Protection Agency (EPA) has
determined that the presence of microbiological
contaminants are a health concern at certain levels of
exposure. If water is inadequately treated,
microbiological contaminants in that water may cause
disease. Disease symptoms may include diarrhea, cramps,
nausea, and possibly jaundice, and any associated
headaches and fatigue. These symptoms, however, are not
just associated with disease-causing organisms in
drinking water, but also may be caused by A number of
factors other than your drinking water. EPA and the state
have set enforceable requirements for treating drinking
water to reduce the risk of these adverse health effects.
Treatment such as filtering and disinfecting the water
removes or destroys microbiological contaminants.
Drinking water which is treated to meet EPA requirements
is associated with little to none of these risk and
should be considered safe.
2.
Total coliform
The
United States Environmental Protection Agency (EPA) has
determined that the presence of total coliforms is a
possible health concern. Total Coliforms are common in
the environment and are generally not harmful themselves.
The presence of these bacteria in drinking water,
however, generally is a result of a problem with water
treatment or the pipes which distribute the water, and
indicates that the water may be contaminated with
organisms that can cause disease. Disease symptoms may
include diarrhea, cramps, nausea, and possibly jaundice,
and any associated headaches and fatigue. These symptoms,
however, are not just associated with disease-causing
organisms in drinking water, but also may be caused by a
number of factors other than your drinking water. EPA and
the state have set an enforceable drinking water standard
for total coliforms to reduce the risk of these adverse
health effects. Under this standard, no more than 5.0
percent of the samples collected during a month can
contain these bacteria, except that systems collecting
fewer than 40 samples/month that have one total
coliform-positive sample per month are not violating the
standard. Drinking water which meets this standard is
usually not associated with a health risk from
disease-causing bacteria and should be considered safe.
3.
Fecal Coliforms/E. coli
The
United States Environmental Protection Agency (EPA) has
determined that the presence of fecal coliforms or E.
coli are generally not harmful themselves, but their
presence in drinking water is serious because they are
usually associated with sewage or animal wastes. The
presence of these bacteria in drinking water generally is
a result of a problem with water treatment or the pipes
which distribute the water, and indicates that the water
may be contaminated with organisms that can cause
disease. Disease symptoms may include diarrhea, cramps,
nausea, and possibly jaundice, and any associated
headaches and fatigue. These symptoms, however, are not
just associated with disease-causing organisms in
drinking water, but also may be caused by a number of
factors other than your drinking water. EPA and the state
have set an enforceable drinking water standard for fecal
coliforms and E. coli to reduce the risk of these adverse
health effects. Under this standard all drinking water
samples must be free of these bacteria. Drinking water
which meets this standard is associated with little or
none of this risk and should be considered safe. State
and local health authorities recommend that consumers
take the following precautions: (To be inserted by the
public water system, according to instructions from the
State or local authorities).
There
are three maximum contaminant levels (MCL) for
microbiological contaminants. The first is based on the
presence or absence of coliform bacteria. This group of
bacteria is very common and is not harmful. The presence
of coliform bacteria is used as an indicator that the
water system must pay closer attention to its
disinfection process. Violation of this MCL is not an
emergency situation.
The
second MCL is based on the presence of fecal coliform or Escherichia
coli (E. coli). Violation of this MCL is an
emergency, and the State requires water systems to
promptly notify the public.
In
addition to the above two MCLs, a third one applies to
public water systems that use surface water or ground
water that is determined to be under the influence of
surface water. Because these type systems are very
susceptible to contamination from bacteria, viruses, and
pathogens like Giardia lamblia and Cryptosporidium,
they are required to filter the water and disinfect it
before sending it to customers. Measures are established
to ensure water from surface water plants is clean.
Violation of this standard is an emergency, and the State
requires water systems to promptly notify the public.
A
public water system must determine its compliance with
the maximum contaminant level for microbiological
contaminants each month (or quarter for non-community
water systems which serve 1,000 or fewer persons).
The
Standard
- The
maximum contaminant level for coliform bacteria is based
on the presence or absence of total coliforms in a
sample, rather than coliform density. For the purpose of
the public notice requirements in Rule 62-560.410,
F.A.C., a violation of the standards in this paragraph
poses a non-acute risk to health.
- For a system which collects at least 40 samples per
month, if no more than 5.0 percent of the samples
collected during a month are total coliform-positive, the
system is in compliance with the maximum contaminant
level for total coliforms.
- For a system which collects fewer than 40 samples per
month, if no more than one sample collected during a
month is total coliform-positive, the system is in
compliance with the maximum contaminant level for total
coliforms.
- Any fecal coliform-positive repeat sample or
E.coli-positive repeat sample, or any total
coliform-positive repeat sample following a fecal
coliform-positive or E.coli-positive routine sample is a
violation of the maximum contaminant level for total
coliforms. For the purposes of the public notification
requirements in Rule 62-560.410, F.A.C., this is a
violation that poses an acute risk to health.
- For surface water systems using conventional or direct filtration,
the turbidity level of representative samples of filtered water taken
throughout the day must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month. At no time is the
turbidity level of the filtered water allowed to exceed
1.0 NTU. In addition to filtration, the water must
contain a disinfectant like chlorine for a predetermined
amount of time before it can be used by the public. For
more detail on this standard, refer to Chapter 62-550.817,
Part VIII, Florida Administrative Code.
2012 State of Florida