| (a) Applicability. All public water systems are subject
to the requirements of this section.
(1) Community and nontransient, noncommunity systems
shall comply with the requirements of this section regarding monitoring,
reporting, and maximum contaminant levels (MCLs) for all inorganic
contaminants (IOCs) listed in this section.
(2) Transient, noncommunity systems shall comply with
the requirements of this section regarding monitoring, reporting,
and MCL for nitrate and nitrite.
(3) For purposes of this section, systems using groundwater
under the direct influence of surface water shall meet the inorganic
sampling requirements given for surface water systems.
(b) MCLs for IOCs. The MCLs for IOCs listed in the
following table apply to community and nontransient, noncommunity
water systems. The MCLs for nitrate, nitrite, and total nitrate and
nitrite also apply to transient, noncommunity water systems.
Attached Graphic
(c) Monitoring requirements for IOCs. Public water
systems shall monitor for IOCs at the locations specified by the executive
director. All monitoring conducted under the requirements of this
section must be conducted at sites designated in the public water
system's monitoring plan. Each public water system shall monitor at
the time designated during each compliance period.
(1) Routine monitoring locations for IOCs except asbestos.
Antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide,
fluoride, mercury, nitrate, nitrite, selenium, and thallium shall
be monitored at each entry point to the distribution system.
(A) If a system draws water from more than one source
and the sources are combined before distribution, the system must
sample at an entry point that is representative of all sources and
during periods of normal operating conditions.
(B) Systems shall take all subsequent samples at the
same entry point to the distribution system unless the executive director
determines that conditions make another entry point more representative
of the source or treatment plant being monitored.
(C) The executive director may approve the use of composite
samples.
(i) Compositing must be done in the laboratory or in
the field by persons designated by the executive director.
(ii) Compositing shall be allowed only at groundwater
entry points to the distribution system.
(iii) Compositing shall be allowed only within a single
system. Samples from different systems shall not be included in a
composite sample.
(iv) No more than five individual samples shall be
included in a composite sample.
(v) The maximum number of individual samples allowed
in a composite sample shall not exceed the number obtained by dividing
the MCL for the contaminant by the detection limit of the analytical
method and rounding the quotient to the next lowest integer. Detection
limits for each analytical method are as listed in 40 Code of Federal
Regulations (CFR) §141.23(a)(4)(i).
(vi) If the concentration in the composite sample is
greater than or equal to the proportional contribution of the MCL
(e.g., 20% of MCL when five points are composited) for any inorganic
chemical, then a follow-up sample must be collected from each sampling
point included in the composite sample.
(I) Follow-up samples must be collected within 14 days
of receipt of the composite sample results.
(II) If duplicates of the original sample taken from
each entry point to the distribution system used in the composite
are available, the system may use these instead of resampling. The
duplicates must be analyzed within 14 days of the composite.
(III) The follow-up or duplicate samples must be analyzed
for the contaminant(s) which were excessive in the composite sample.
(D) Initial monitoring for a new water source must
be conducted at a site representative of the water quality of the
new source of water. For systems with one well and one entry point,
initial monitoring may be conducted at the entry point to the distribution
system.
(2) Monitoring locations for asbestos. Asbestos shall
be monitored at locations where asbestos contamination is most likely
to occur.
(A) A system vulnerable to asbestos contamination due
solely to source water shall sample at the entry point to the distribution
system.
(B) A system vulnerable to asbestos contamination due
solely to corrosion of asbestos-cement pipe shall sample at a tap
served by asbestos-cement pipe, under conditions where asbestos contamination
is most likely to occur.
(C) A system vulnerable to asbestos contamination due
both to its source water supply and corrosion of asbestos-cement pipe
shall sample at a tap served by asbestos-cement pipe, under conditions
where asbestos contamination is most likely to occur.
(D) The executive director may require additional sampling
locations based on the size, length, age, and location of asbestos-cement
pipe in the distribution system. The system must provide information
regarding the size, length, age, and location of asbestos-cement pipe
in the distribution system to the executive director upon request.
(3) Initial monitoring frequency for IOCs except asbestos.
Prior to using water as a drinking water source, public water systems
shall monitor at the frequency determined by the executive director
to ensure that the water distributed to customers will comply with
the MCLs for antimony, arsenic, barium, beryllium, cadmium, chromium,
cyanide, fluoride, nitrate, nitrite, nitrate and nitrite (total),
mercury, selenium, and thallium.
(4) Monitoring frequency for IOCs except asbestos,
nitrate, and nitrite. Community and nontransient, noncommunity public
water systems shall monitor for antimony, arsenic, barium, beryllium,
cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium
at the following frequency.
(A) Routine monitoring frequency. A public water system
shall routinely monitor for antimony, arsenic, barium, beryllium,
cadmium, chromium, cyanide, fluoride, mercury, selenium, and thallium.
(i) Each groundwater entry point shall be sampled once
every three years.
(ii) Each surface water entry point shall be sampled
annually.
(iii) Each of the sampling frequencies listed in this
paragraph constitutes one round of sampling for groundwater and surface
water entry points, respectively.
(B) Reduced monitoring. The executive director may
reduce the monitoring frequency for a system that has completed a
minimum of three rounds of sampling by granting a waiver to the routine
monitoring frequency for antimony, arsenic, barium, beryllium, cadmium,
chromium, cyanide, fluoride, mercury, selenium, and thallium.
(i) Systems that use a new water source are not eligible
for a waiver until three rounds of sampling from the new source have
been completed.
(ii) To be considered for a waiver, systems shall demonstrate
that all previous analytical results at that sample site were less
than the MCL.
(iii) In determining the appropriate reduced monitoring
frequency, the executive director shall consider:
(I) the reported contaminant concentrations from all
previous samples;
(II) the degree of variation in reported concentrations;
and
(III) other factors that may affect contaminant concentrations
such as changes in groundwater pumping rates, changes in the system's
configuration, changes in the system's operating procedures, or changes
in the flow or characteristics of a reservoir or stream used as the
water source.
(iv) If the executive director grants a waiver, it
shall be made in writing and shall set forth the basis for the determination.
The determination may be initiated by the executive director. The
executive director shall review and, where appropriate, revise the
waiver of monitoring frequency when other data relevant to the system
becomes available.
(v) The term during which the waiver is effective shall
not exceed one compliance cycle (i.e., nine years).
(vi) A system must take a minimum of one sample during
each compliance cycle while the waiver is effective.
(C) Increased monitoring. The executive director may
increase the monitoring frequency for antimony, arsenic, barium, beryllium,
cadmium, chromium, cyanide, fluoride, mercury, selenium, or thallium.
(i) If the results from a sample site exceed any of
the MCLs in subsection (b) of this section, the system shall immediately
begin quarterly sampling at that sample site starting in the next
quarter after the exceedance occurs.
(ii) After the initiation of quarterly monitoring,
the executive director may return a system to the routine monitoring
frequency if monitoring shows that the sampling site is reliably and
consistently below the MCL.
(I) The executive director shall not decrease the quarterly
sampling requirement until a groundwater system has taken a minimum
of two quarterly samples.
(II) The executive director shall not decrease the
quarterly sampling requirement until a surface water system has taken
a minimum of four quarterly samples.
(5) Asbestos monitoring frequency. Community and nontransient,
noncommunity water systems shall monitor for asbestos at the following
frequency.
(A) A public water system shall routinely monitor for
asbestos once during the first three years of each compliance cycle.
(B) The executive director may waive the routine monitoring
frequency requirements for asbestos.
(i) When determining if a waiver should be granted,
the executive director shall consider:
(I) the potential for asbestos contamination of the
water source;
(II) the use of asbestos-cement pipe for finished water
distribution; and
(III) the corrosivity of the water.
(ii) If the executive director grants a waiver, it
shall be made in writing and shall set forth the basis for the determination.
The determination may be initiated by the executive director. The
executive director shall review and, where appropriate, revise the
waiver of monitoring frequency when other data relevant to the system
becomes available.
(iii) The term during which the waiver is effective
shall not exceed one compliance cycle (i.e., nine years).
(C) The executive director may increase the monitoring
frequency for asbestos.
(i) A system that exceeds the MCL for asbestos shall
sample quarterly beginning in the next quarter after the violation
occurs.
(ii) After the initiation of quarterly sampling, the
executive director may return a system to the routine monitoring frequency
if monitoring shows that the system is reliably and consistently below
the MCL.
(I) The executive director shall not decrease the quarterly
sampling requirement until a groundwater system has taken a minimum
of two quarterly samples.
(II) The executive director shall not decrease the
quarterly sampling requirement until a surface (or combined surface
water and groundwater) water system has taken a minimum of four quarterly
samples.
(6) Nitrate monitoring frequency. All public water
systems shall monitor for nitrate at the following frequency.
(A) Routine nitrate monitoring frequency. All public
water systems shall routinely monitor for nitrate.
(i) All public water systems shall annually sample
at each groundwater entry point to the distribution system.
(ii) A community or nontransient, noncommunity water
system shall sample quarterly at each surface water entry point to
the distribution system.
(iii) A transient, noncommunity water system shall
sample annually at each surface water entry point to the distribution
system.
(B) Reduced nitrate monitoring frequency. The executive
director may reduce the monitoring frequency for community or nontransient,
noncommunity water systems using surface water sources by granting
a waiver to the routine monitoring frequency.
(i) To be considered for a waiver, a system shall demonstrate
that the nitrate concentration in each sample collected during the
previous four consecutive quarters was less than 50% of the nitrate
MCL.
(ii) If the executive director grants a waiver, it
shall be made in writing and shall set forth the basis for the determination.
The determination may be initiated by the executive director. The
executive director shall review and, where appropriate, revise the
waiver of monitoring frequency when other data relevant to the system
becomes available.
(iii) A system that receives a waiver to the routine
nitrate monitoring frequency must sample annually for nitrate. The
annual sample must be collected in the quarter that previously resulted
in the highest nitrate concentration.
(C) Increased nitrate monitoring frequency. The executive
director may increase the nitrate monitoring frequency for community
or nontransient, noncommunity water systems using groundwater sources.
(i) A system that is sampling annually shall begin
quarterly nitrate sampling if the nitrate concentration in any sample
is equal to or greater than 50% of the nitrate MCL. Quarterly sampling
must begin the first quarter after the elevated nitrate level was
detected.
Cont'd... |
