United States
Environmental Protection
Agency
Office of Water
4601
EPA 570/9-91-200
January 1995
EPA Total Coliform Rule
"Water systems
must test for
bacteria in the
water supply."
The Total Coliform Rule was published in The Federal Register on June 29,
1989. It became effective December 31, 1990. This rule established microbiological
standards and monitoring requirements which apply to all community and non-
community water systems.
Water Quality Standards
Table 1. Coliform MCLs
# of Routine
Samples/Month
Limits for Total Coliform-
Positive Samples Each Month
Less than 40/mo.
40/mo. or more
No more than one sample
No more than five percent
of all monthly samples.
Maximum Contaminant Level Goals (MCLG): Zero
Water systems should try to achieve coliform-free water.
This is a non-enforceable health goal.
Maximum Contaminant Levels (MCL): Presence/Absence
of total coliforms. (Table 1)
The presence of total coliform bacteria indicates the
possible presence of fecal and disease-causing bacteria.
Enforceable standards are set for total and fecal coliforms.
Table 2. Routine Sampling
Community Systems*
Population Routine Samples/Mo.
25-1000 1
4101-4900 5
8501-12,900 10
17,201-21,500 20
41,001-50,000 50
96,001-130,000 100
450,001-600,00 210
2,270,001-3,020,000 420
3,960,001 or more 480
*For complete listing, see the Federal Register.
Non-Community Systems
Source type Population Frequency
GW <1000 1 per qtr
GW >1000 SameasCWS
SW Same as CWS
GW-UDI Same as CWS
Monitoring Requirements
Routine Sampling (Table 2)
• Sampling by community water systems (CWS) is done at intervals
during each month with the number of monthly samples based on
the population served.
• For non-community water systems (NCWS), the number of monthly
samples also depends on whether the water source used is surface
water i SW), groundwater (GW) or groundwater under the direct
influence of surface water (GW-UDI). Under some conditions the
State may reduce the sampling frequency to no less than 1 per year.
• Unfiltered surface water systems and unfiltered groundwater
systems under the direct influence of surface water must analyze
one coliform sample near the first service connection each day the
source water exceeds the turbidity standard.
Repeat Sampling
• Repeat sampling is required according to Table 3. If a routine
sample is total coli form-positive, repeat sampling must be done
within 24 hours of notification of a positive sample. Systems must
take a certain number of repeat samples for EACH routine or
repeat sample found to be total coliform-positive. The State may
extend the 24-hr, limit but may not waive this type of repeat
sampling.
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• Small systems collecting fewer than five routine samples per
month must collect five routine samples in the month following
a total coliform-positive routine sample. Under some conditions,
the State may waive this type of repeat sampling.
• The State may invalidate the results of total coliform-positive
samples only if it determines the results are due to laboratory
error or some other condition which does not reflect the actual
water quality within the distribution system.
Compliance
Table 3. Repeat Sampling
Original Routine
Samples/Mo.
Repeat
Samples
Routine Samples
Next Mo.
1/mo.
2/mo.
3/mo.
4/mo.
5/mo. or more
* = same as original routine frequency.
Systems were required to begin complying with all monitoring and analytical
requirements on December 31, 1990.
• The MCL is based on the presence or absence of coliforms in a percentage of
all samples taken each month. If any sample is total coliform-positive,
- that sample must also be tested for fecal coliforms or E. coli AND
- repeat samples must be taken, according to Table 3.
• The MCL is exceeded if
- the limits given in Table 1 are exceeded, OR
- any repeat sample is positive for fecal coliforms or E. coli, OR
- a routine sample which is positive for fecal coliforms or E. coli is followed
by a total coliform-positive repeat sample.
• If fecal coliforms or E. coli are detected in any total coliform-positive sample,
the system must notify the State immediately.
• The State may allow a water system to forgo fecal coliform or E. coli testing
on a case-by-case basis if the system responds to every total coliform-positive
sample as if it contained fecal coliforms.
Sanitary Surveys
Sanitary surveys are required for all systems collecting fewer than 5 samples/
month. The initial surveys must be completed by June 29, 1994 for community
water systems and June 29, 1999 for non-community systems. Subsequent surveys
must be conducted every five years. Non-community systems using only protected,
disinfected groundwater must repeat surveys every ten years.
Variances and Exemptions
States may allow variances for systems having persistent total coliforms due to
distribution system problems, but only those systems which are not at risk of fecal
or pathogenic contamination will be eligible. This means there must have been no
treatment lapses or deficiencies, no measured fecal or pathogenic contamination,
or improper operation or maintenance of the distribution systems. No exemptions
will be allowed.
For More Information
Call the Safe Drinking Water Hotline at 1-800-426-4791
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