[Code of Federal Regulations]
[Title 40, Volume 22]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR141.26]

[Page 385-389]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 141_NATIONAL PRIMARY DRINKING WATER REGULATIONS--Table of Contents
 
            Subpart C_Monitoring and Analytical Requirements
 
Sec.  141.26  Monitoring frequency and compliance requirements for 
radionuclides in community water systems.

    (a) Monitoring and compliance requirements for gross alpha particle 
activity, radium-226, radium-228, and uranium. (1) Community water 
systems (CWSs) must conduct initial monitoring to determine compliance 
with Sec.  141.66(b), (c), and (e) by December 31, 2007. For the 
purposes of monitoring for gross alpha particle activity, radium-226, 
radium-228, uranium, and beta particle and photon radioactivity in 
drinking water, ``detection limit'' is defined as in Sec.  141.25(c).
    (i) Applicability and sampling location for existing community water 
systems or sources. All existing CWSs using ground water, surface water 
or systems using both ground and surface water (for the purpose of this 
section hereafter referred to as systems) must sample at every entry 
point to the distribution system that is representative of all sources 
being used (hereafter called a sampling point) under normal operating 
conditions. The system must take each sample at the same sampling point 
unless conditions make another sampling point more representative of 
each source or the State has designated a distribution system location, 
in accordance with paragraph (a)(2)(ii)(C) of this section.
    (ii) Applicability and sampling location for new community water 
systems or sources. All new CWSs or CWSs that use a new source of water 
must begin to conduct initial monitoring for the new source within the 
first quarter after

[[Page 386]]

initiating use of the source. CWSs must conduct more frequent monitoring 
when ordered by the State in the event of possible contamination or when 
changes in the distribution system or treatment processes occur which 
may increase the concentration of radioactivity in finished water.
    (2) Initial monitoring: Systems must conduct initial monitoring for 
gross alpha particle activity, radium-226, radium-228, and uranium as 
follows:
    (i) Systems without acceptable historical data, as defined below, 
must collect four consecutive quarterly samples at all sampling points 
before December 31, 2007.
    (ii) Grandfathering of data: States may allow historical monitoring 
data collected at a sampling point to satisfy the initial monitoring 
requirements for that sampling point, for the following situations.
    (A) To satisfy initial monitoring requirements, a community water 
system having only one entry point to the distribution system may use 
the monitoring data from the last compliance monitoring period that 
began between June 2000 and December 8, 2003.
    (B) To satisfy initial monitoring requirements, a community water 
system with multiple entry points and having appropriate historical 
monitoring data for each entry point to the distribution system may use 
the monitoring data from the last compliance monitoring period that 
began between June 2000 and December 8, 2003.
    (C) To satisfy initial monitoring requirements, a community water 
system with appropriate historical data for a representative point in 
the distribution system may use the monitoring data from the last 
compliance monitoring period that began between June 2000 and December 
8, 2003, provided that the State finds that the historical data 
satisfactorily demonstrate that each entry point to the distribution 
system is expected to be in compliance based upon the historical data 
and reasonable assumptions about the variability of contaminant levels 
between entry points. The State must make a written finding indicating 
how the data conforms to the these requirements.
    (iii) For gross alpha particle activity, uranium, radium-226, and 
radium-228 monitoring, the State may waive the final two quarters of 
initial monitoring for a sampling point if the results of the samples 
from the previous two quarters are below the detection limit.
    (iv) If the average of the initial monitoring results for a sampling 
point is above the MCL, the system must collect and analyze quarterly 
samples at that sampling point until the system has results from four 
consecutive quarters that are at or below the MCL, unless the system 
enters into another schedule as part of a formal compliance agreement 
with the State.
    (3) Reduced monitoring: States may allow community water systems to 
reduce the future frequency of monitoring from once every three years to 
once every six or nine years at each sampling point, based on the 
following criteria.
    (i) If the average of the initial monitoring results for each 
contaminant (i.e., gross alpha particle activity, uranium, radium-226, 
or radium-228) is below the detection limit specified in Table B, in 
Sec.  141.25(c)(1), the system must collect and analyze for that 
contaminant using at least one sample at that sampling point every nine 
years.
    (ii) For gross alpha particle activity and uranium, if the average 
of the initial monitoring results for each contaminant is at or above 
the detection limit but at or below \1/2\ the MCL, the system must 
collect and analyze for that contaminant using at least one sample at 
that sampling point every six years. For combined radium-226 and radium-
228, the analytical results must be combined. If the average of the 
combined initial monitoring results for radium-226 and radium-228 is at 
or above the detection limit but at or below \1/2\ the MCL, the system 
must collect and analyze for that contaminant using at least one sample 
at that sampling point every six years.
    (iii) For gross alpha particle activity and uranium, if the average 
of the initial monitoring results for each contaminant is above \1/2\ 
the MCL but at or below the MCL, the system must collect and analyze at 
least one sample at that sampling point every three years. For combined 
radium-226 and radium-

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228, the analytical results must be combined. If the average of the 
combined initial monitoring results for radium-226 and radium-228 is 
above \1/2\ the MCL but at or below the MCL, the system must collect and 
analyze at least one sample at that sampling point every three years.
    (iv) Systems must use the samples collected during the reduced 
monitoring period to determine the monitoring frequency for subsequent 
monitoring periods (e.g., if a system's sampling point is on a nine year 
monitoring period, and the sample result is above \1/2\ MCL, then the 
next monitoring period for that sampling point is three years).
    (v) If a system has a monitoring result that exceeds the MCL while 
on reduced monitoring, the system must collect and analyze quarterly 
samples at that sampling point until the system has results from four 
consecutive quarters that are below the MCL, unless the system enters 
into another schedule as part of a formal compliance agreement with the 
State.
    (4) Compositing: To fulfill quarterly monitoring requirements for 
gross alpha particle activity, radium-226, radium-228, or uranium, a 
system may composite up to four consecutive quarterly samples from a 
single entry point if analysis is done within a year of the first 
sample. States will treat analytical results from the composited as the 
average analytical result to determine compliance with the MCLs and the 
future monitoring frequency. If the analytical result from the 
composited sample is greater than \1/2\ MCL, the State may direct the 
system to take additional quarterly samples before allowing the system 
to sample under a reduced monitoring schedule.
    (5) A gross alpha particle activity measurement may be substituted 
for the required radium-226 measurement provided that the measured gross 
alpha particle activity does not exceed 5 pCi/l. A gross alpha particle 
activity measurement may be substituted for the required uranium 
measurement provided that the measured gross alpha particle activity 
does not exceed 15 pCi/l. The gross alpha measurement shall have a 
confidence interval of 95% (1.65[sigma], where [sigma] is the standard 
deviation of the net counting rate of the sample) for radium-226 and 
uranium. When a system uses a gross alpha particle activity measurement 
in lieu of a radium-226 and/or uranium measurement, the gross alpha 
particle activity analytical result will be used to determine the future 
monitoring frequency for radium-226 and/or uranium. If the gross alpha 
particle activity result is less than detection, \1/2\ the detection 
limit will be used to determine compliance and the future monitoring 
frequency.
    (b) Monitoring and compliance requirements for beta particle and 
photon radioactivity. To determine compliance with the maximum 
contaminant levels in Sec.  141.66(d) for beta particle and photon 
radioactivity, a system must monitor at a frequency as follows:
    (1) Community water systems (both surface and ground water) 
designated by the State as vulnerable must sample for beta particle and 
photon radioactivity. Systems must collect quarterly samples for beta 
emitters and annual samples for tritium and strontium-90 at each entry 
point to the distribution system (hereafter called a sampling point), 
beginning within one quarter after being notified by the State. Systems 
already designated by the State must continue to sample until the State 
reviews and either reaffirms or removes the designation.
    (i) If the gross beta particle activity minus the naturally 
occurring potassium-40 beta particle activity at a sampling point has a 
running annual average (computed quarterly) less than or equal to 50 
pCi/L (screening level), the State may reduce the frequency of 
monitoring at that sampling point to once every 3 years. Systems must 
collect all samples required in paragraph (b)(1) of this section during 
the reduced monitoring period.
    (ii) For systems in the vicinity of a nuclear facility, the State 
may allow the CWS to utilize environmental surveillance data collected 
by the nuclear facility in lieu of monitoring at the system's entry 
point(s), where the State determines if such data is applicable to a 
particular water system. In the event that there is a release from a 
nuclear facility, systems which are using surveillance data must begin 
monitoring at the community water

[[Page 388]]

system's entry point(s) in accordance with paragraph (b)(1) of this 
section.
    (2) Community water systems (both surface and ground water) 
designated by the State as utilizing waters contaminated by effluents 
from nuclear facilities must sample for beta particle and photon 
radioactivity. Systems must collect quarterly samples for beta emitters 
and iodine-131 and annual samples for tritium and strontium-90 at each 
entry point to the distribution system (hereafter called a sampling 
point), beginning within one quarter after being notified by the State. 
Systems already designated by the State as systems using waters 
contaminated by effluents from nuclear facilities must continue to 
sample until the State reviews and either reaffirms or removes the 
designation.
    (i) Quarterly monitoring for gross beta particle activity shall be 
based on the analysis of monthly samples or the analysis of a composite 
of three monthly samples. The former is recommended.
    (ii) For iodine-131, a composite of five consecutive daily samples 
shall be analyzed once each quarter. As ordered by the State, more 
frequent monitoring shall be conducted when iodine-131 is identified in 
the finished water.
    (iii) Annual monitoring for strontium-90 and tritium shall be 
conducted by means of the analysis of a composite of four consecutive 
quarterly samples or analysis of four quarterly samples. The latter 
procedure is recommended.
    (iv) If the gross beta particle activity minus the naturally 
occurring potassium-40 beta particle activity at a sampling point has a 
running annual average (computed quarterly) less than or equal to 15 
pCi/L (screening level), the State may reduce the frequency of 
monitoring at that sampling point to every 3 years. Systems must collect 
the same type of samples required in paragraph (b)(2) of this section 
during the reduced monitoring period.
    (v) For systems in the vicinity of a nuclear facility, the State may 
allow the CWS to utilize environmental surveillance data collected by 
the nuclear facility in lieu of monitoring at the system's entry 
point(s), where the State determines if such data is applicable to a 
particular water system. In the event that there is a release from a 
nuclear facility, systems which are using surveillance data must begin 
monitoring at the community water system's entry point(s) in accordance 
with paragraph (b)(2) of this section.
    (3) Community water systems designated by the State to monitor for 
beta particle and photon radioactivity can not apply to the State for a 
waiver from the monitoring frequencies specified in paragraph (b)(1) or 
(b)(2) of this section.
    (4) Community water systems may analyze for naturally occurring 
potassium-40 beta particle activity from the same or equivalent sample 
used for the gross beta particle activity analysis. Systems are allowed 
to subtract the potassium-40 beta particle activity value from the total 
gross beta particle activity value to determine if the screening level 
is exceeded. The potassium-40 beta particle activity must be calculated 
by multiplying elemental potassium concentrations (in mg/L) by a factor 
of 0.82.
    (5) If the gross beta particle activity minus the naturally 
occurring potassium-40 beta particle activity exceeds the appropriate 
screening level, an analysis of the sample must be performed to identify 
the major radioactive constituents present in the sample and the 
appropriate doses must be calculated and summed to determine compliance 
with Sec.  141.66(d)(1), using the formula in Sec.  141.66(d)(2). Doses 
must also be calculated and combined for measured levels of tritium and 
strontium to determine compliance.
    (6) Systems must monitor monthly at the sampling point(s) which 
exceed the maximum contaminant level in Sec.  141.66(d) beginning the 
month after the exceedance occurs. Systems must continue monthly 
monitoring until the system has established, by a rolling average of 3 
monthly samples, that the MCL is being met. Systems who establish that 
the MCL is being met must return to quarterly monitoring until they meet 
the requirements set forth in paragraph (b)(1)(i) or (b)(2)(iv) of this 
section.
    (c) General monitoring and compliance requirements for 
radionuclides. (1) The

[[Page 389]]

State may require more frequent monitoring than specified in paragraphs 
(a) and (b) of this section, or may require confirmation samples at its 
discretion. The results of the initial and confirmation samples will be 
averaged for use in compliance determinations.
    (2) Each public water systems shall monitor at the time designated 
by the State during each compliance period.
    (3) Compliance: Compliance with Sec.  141.66 (b) through (e) will be 
determined based on the analytical result(s) obtained at each sampling 
point. If one sampling point is in violation of an MCL, the system is in 
violation of the MCL.
    (i) For systems monitoring more than once per year, compliance with 
the MCL is determined by a running annual average at each sampling 
point. If the average of any sampling point is greater than the MCL, 
then the system is out of compliance with the MCL.
    (ii) For systems monitoring more than once per year, if any sample 
result will cause the running average to exceed the MCL at any sample 
point, the system is out of compliance with the MCL immediately.
    (iii) Systems must include all samples taken and analyzed under the 
provisions of this section in determining compliance, even if that 
number is greater than the minimum required.
    (iv) If a system does not collect all required samples when 
compliance is based on a running annual average of quarterly samples, 
compliance will be based on the running average of the samples 
collected.
    (v) If a sample result is less than the detection limit, zero will 
be used to calculate the annual average, unless a gross alpha particle 
activity is being used in lieu of radium-226 and/or uranium. If the 
gross alpha particle activity result is less than detection, \1/2\ the 
detection limit will be used to calculate the annual average.
    (4) States have the discretion to delete results of obvious sampling 
or analytic errors.
    (5) If the MCL for radioactivity set forth in Sec.  141.66 (b) 
through (e) is exceeded, the operator of a community water system must 
give notice to the State pursuant to Sec.  141.31 and to the public as 
required by subpart Q of this part.

[65 FR 76745, Dec. 7, 2000, as amended at 69 FR 38855, June 29, 2004]