| (B) Public water systems shall collect distribution
coliform samples at locations specified in the public water system's
Sample Siting Plan which shall be included in the public water system's
monitoring plan.
(2) Routine distribution coliform sampling frequency.
All public water systems must sample for distribution coliform at
the following frequency.
(A) Community and noncommunity public water systems
must collect routine distribution coliform samples at a frequency
based on the population served by the system.
(i) The population for noncommunity systems will be
based on the maximum number of persons served on any given day during
the month based on the data reported by the public water system to
the executive director during the most recent sanitary survey of the
public water system or any other data as required by the executive
director.
(ii) The population of community systems will be based
on the data reported by the public water system to the executive director
during the most recent sanitary survey of the public water system
or any other data as required by the executive director.
(iii) The minimum sampling frequency for public water
systems is shown in the following table.
Attached Graphic
(B) A public water system which uses surface water
or groundwater under the direct influence of surface water must collect
routine distribution coliform samples at regular time intervals throughout
the month.
(C) A public water system which uses only purchased
water or groundwater not under the direct influence of surface water
and serves more than 4,900 persons must collect routine distribution
coliform samples at regular time intervals throughout the month.
(D) A public water system which uses only purchased
water or groundwater not under the direct influence of surface water
and serves 4,900 persons or fewer may collect all required routine
distribution coliform samples on a single day if they are taken from
different sites.
(E) A total coliform-positive sample invalidated under
this subsection does not count towards meeting the minimum routine
monitoring requirements of this subsection. Unless the executive director
has invalidated the sample in accordance with subsection (e) of this
section, all routine coliform sample results must be used to determine
compliance with subsection (b)(1) of this section and to determine
treatment technique trigger and assessment requirements as described
in subsection (c)(1) and (2) of this section.
(F) All public water system shall collect at least
the minimum number of required routine microbial samples even if the
public water system has had an E. coli MCL
violation under any of the conditions as described in subsection (b)(1)(A)
- (D) of this section or has exceeded the coliform treatment technique
triggers as described in subsection (c)(1) and (2) of this section.
(G) A public water system may conduct more microbial
compliance monitoring than is required by this subsection to investigate
potential problems in the public water system treatment facilities
and distribution system and use monitoring to assist in identifying
problems. A public water system may collect more than the minimum
number of required routine samples required by this subsection. A
public water system that collects more than the minimum number of
required routine samples required by this subsection shall include
the results of these samples in calculating whether the coliform treatment
technique triggers as described in subsection (c)(1) and (2) of this
section have been exceeded. The additional routine sample sites shall
be included in the public water system's Sample Siting Plan and collected
in accordance with the Sample Siting Plan and shall be representative
of water throughout the distribution system.
(3) Repeat distribution coliform sampling requirements.
Public water systems shall conduct repeat monitoring if one or more
of the routine samples is found to contain coliform organisms.
(A) If a routine distribution coliform sample is coliform-positive,
the public water system must collect a set of repeat distribution
coliform samples within 24 hours of being notified of the positive
result, or as soon as possible if the local laboratory is closed.
The executive director may extend the 24-hour limit on a case-by-case
basis if the public water system has a logistical problem in collecting
the repeat samples within 24 hours that is beyond the public water
system's control. All public water systems shall collect no fewer
than three repeat samples for each total coliform-positive sample
found even if the public water system has had an E. coli MCL violation under any of the conditions
as described in subsection (b)(1)(A) - (D) of this section or has
exceeded the coliform treatment technique triggers as described in
subsection (c)(1) and (2) of this section.
(B) The public water system must collect all repeat
samples on the same day, except a public water system with a single
service connection may collect daily repeat samples over a three-day
period until the required number of repeat samples has been collected.
(C) Unless the public water system meets the provisions
of clause (i) or (ii) of this subparagraph, the public water system
must collect at least one repeat sample from the sampling tap where
the original coliform-positive sample was taken, and at least one
repeat sample at a tap within five service connections upstream and
at least one repeat sample at a tap within five service connections
downstream of the original sampling site. If the positive routine
sample was collected at the end of the distribution system, or one
service connection away from the end of the distribution system, one
repeat sample must be collected at that point and the other two repeat
samples must be collected within five connections upstream of that
point.
(i) As approved by the executive director, public water
systems may propose repeat monitoring locations to the executive director
that the public water system considers to be representative of a pathway
for contamination of the distribution system. A public water system
may elect to specify either alternative fixed locations or criteria
for selecting repeat sampling sites on a situational basis in a written
standard operating procedure (SOP) in its Sample Siting Plan. The
public water system shall design its SOP to focus the repeat samples
at locations that best verify and determine the extent of potential
contamination of the distribution system area based on specific situations.
The executive director may modify the SOP or require alternative monitoring
locations as needed.
(ii) As approved by the executive director, groundwater
public water systems serving 1,000 or fewer people may propose repeat
sampling locations to the executive director, in a written SOP in
its Sample Siting Plan, that differentiate potential source water
and distribution system contamination (e.g., by sampling at entry
points to the distribution system). A groundwater public water system
with a single well required to conduct triggered source water monitoring
may, with written executive director approval, take one of its repeat
samples at the monitoring location required for triggered source water
monitoring under paragraph (4) and (4)(A) of this subsection if the
public water system demonstrates to the executive director that the
Sample Siting Plan remains representative of water quality in the
distribution system. If approved by the executive director, the public
water system may use that sample result to meet the monitoring requirements
for both repeat monitoring under this paragraph and triggered source
monitoring under paragraph (4) and (4)(A) of this subsection.
(iii) All public water systems shall include all sample
sites as required by this subparagraph and any required SOPs for any
proposed sampling sites as described in clauses (i) and (ii) of this
subparagraph in the public water system's Sample Siting Plan in accordance
with paragraph (6) of this subsection.
(D) If one or more repeat samples in the set is total
coliform-positive, the public water system must collect an additional
set of repeat samples in the manner specified in subparagraphs (A)
- (C) of this paragraph. The additional samples must be collected
within 24 hours of the public water system being notified of the positive
result or as soon as possible if the local laboratory is closed. The
executive director may extend the 24-hour limit on a case-by-case
basis if the public water system has a logistical problem in collecting
the repeat samples within 24 hours that is beyond the public water
system's control. In accordance with 40 Code of Federal Regulations
(CFR) §141.858(a)(1) the executive director is prohibited from
waiving the requirement for a public water system to collect repeat
samples as specified in subparagraphs (A) - (D) of this paragraph.
The public water system must repeat this process until either one
of the following occurs:
(i) total coliforms are not detected in one complete
set of repeat samples;
(ii) a coliform treatment technique trigger as described
in subsection (c)(1) and (2) of this section has been exceeded; or
Cont'd... |
