Science of Water : Concepts and Applications

Environmental Biomonitoring, Sampling, and Testing 277
Routine Sampling Requirements
1. Total coliform samples must be collected at sites, which are representative of water quality
throughout the distribution system according to a written sample siting plan subject to
state review and revision.
2. Samples must be collected at regular time intervals throughout the month except groundwater
systems serving 4900 persons or fewer may be collected on the same day.
3. Monthly sampling requirements are based on population served.
4. A reduced monitoring frequency may be available for systems serving 1000 persons or
fewer and using only groundwater if a sanitary survey within the past 5 years shows that
the system is free of sanitary defects (the frequency may be no less than 1 sample/quarter
for community and 1 sample/year for noncommunity systems).
5. Each total coliform-positive routine sample must be tested for the presence of fecal coliforms
or E. coli.
Repeat Sampling Requirements
1. Within 24 h of learning of a total coliform-positive ROUTINE sample result, at least
three REPEAT samples must be collected and analyzed for total coliforms.
2. One REPEAT sample must be collected from the same tap as the original sample.
3. One REPEAT sample must be collected within fi ve service connections upstream.
4. One REPEAT sample must be collected within fi ve service connections downstream.
5. Systems that collect 1 ROUTINE sample per month or fewer must collect a fourth REPEAT
sample.
6. If any REPEAT sample is total coliform-positive:
a. The system must analyze that total coliform-positive culture for fecal coliforms or
E. coli.
b. The system must collect another set of REPEAT samples, as before, unless the MCL
has been violated and the system has notifi ed the state.
Additional Routine Sample Requirements
A positive ROUTINE or REPEAT total coliform result requires a minimum of fi ve ROUTINE
samples be collected the following month the system provides water to the public unless waived by
the state. Public system ROUTINE monitoring frequency is shown in Table 8.9.
Other Total Coliform Rule Provisions
1. Systems collecting fewer than fi ve ROUTINE samples per month must have a sanitary survey
every 5 years (or every 10 years if it is a noncommunity water system using protected
and disinfected groundwater).
2. Systems using surface water or groundwater under the direct infl uence of surface water
(GWUDI) and meeting fi ltration avoidance criteria must collect and have one coliform
sample analyzed each day if the turbidity of the source water exceeds 1 NTU. This sample
must be collected from a tap near the fi rst service connection.
Compliance
Compliance is based on the presence or absence of total coliforms. Moreover, compliance is determined
each calendar month the system serves water to the public (or each calendar month that sampling
occurs for systems on reduced monitoring). The results of ROUTINE and REPEAT samples
are used to calculate compliance.
With regard to violations, a monthly MCL violation is triggered if a system collecting fewer
than 40 samples per month has greater than 1 ROUTINE/REPEAT sample per month, which is
total coliform-positive. In addition, if a system collecting at least 40 samples per month has greater
than 5% of the ROUTINE/REPEAT samples in a month total coliform-positive, it is technically in
violation of the Total Coliform Rule. An acute MCL violation is triggered if any public water system