[Code of Federal Regulations]
[Title 40, Volume 22]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR141.86]

[Page 478-485]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 141_NATIONAL PRIMARY DRINKING WATER REGULATIONS--Table of Contents
 
                  Subpart I_Control of Lead and Copper
 
Sec. 141.86  Monitoring requirements for lead and copper in tap water.

    (a) Sample site location. (1) By the applicable date for 
commencement of monitoring under paragraph (d)(1) of this section, each 
water system shall complete a materials evaluation of its distribution 
system in order to identify a pool of targeted sampling sites that meets 
the requirements of this section, and which is sufficiently large to 
ensure that the water system can collect the number of lead and copper 
tap samples required in paragraph (c) of this section. All sites from 
which first draw samples are collected shall be selected from this pool 
of targeted sampling sites. Sampling sites may not include faucets that 
have point-of-use or point-of-entry treatment devices designed to remove 
inorganic contaminants.
    (2) A water system shall use the information on lead, copper, and 
galvanized steel that it is required to collect under Sec. 141.42(d) of 
this part [special monitoring for corrosivity characteristics] when 
conducting a materials evaluation. When an evaluation of the information 
collected pursuant to Sec. 141.42(d) is insufficient to locate the 
requisite number of lead and copper sampling sites that meet the 
targeting criteria in paragraph (a) of this section, the water system 
shall review the sources of information listed below in order to 
identify a sufficient number of sampling sites. In addition, the system 
shall seek to collect such information where possible in the course of 
its normal operations (e.g., checking service line materials when 
reading water meters or performing maintenance activities):
    (i) All plumbing codes, permits, and records in the files of the 
building department(s) which indicate the plumbing materials that are 
installed within publicly and privately owned structures connected to 
the distribution system;
    (ii) All inspections and records of the distribution system that 
indicate the material composition of the service connections that 
connect a structure to the distribution system; and
    (iii) All existing water quality information, which includes the 
results of all prior analyses of the system or individual structures 
connected to the system, indicating locations that may be particularly 
susceptible to high lead or copper concentrations.
    (3) The sampling sites selected for a community water system's 
sampling pool (``tier l sampling sites'') shall consist of single family 
structures that:
    (i) Contain copper pipes with lead solder installed after 1982 or 
contain lead pipes; and/or
    (ii) Are served by a lead service line. When multiple-family 
residences comprise at least 20 percent of the structures served by a 
water system, the system may include these types of structures in its 
sampling pool.
    (4) Any community water system with insufficient tier 1 sampling 
sites shall complete its sampling pool with ``tier 2 sampling sites'', 
consisting of buildings, including multiple-family residences that:
    (i) Contain copper pipes with lead solder installed after 1982 or 
contain lead pipes; and/or
    (ii) Are served by a lead service line.
    (5) Any community water system with insufficient tier 1 and tier 2 
sampling sites shall complete its sampling pool with ``tier 3 sampling 
sites'', consisting of single family structures that contain copper 
pipes with lead solder installed before 1983. A community water system 
with insufficient tier 1, tier 2, and tier 3 sampling sites shall 
complete its sampling pool with representative sites throughout the 
distribution system. For the purpose of this paragraph, a representative 
site is a site in which the plumbing materials used at that site would 
be commonly found at other sites served by the water system.
    (6) The sampling sites selected for a non-transient noncommunity 
water system (``tier l sampling sites'') shall consist of buildings 
that:
    (i) Contain copper pipes with lead solder installed after 1982 or 
contain lead pipes; and/or
    (ii) Are served by a lead service line.
    (7) A non-transient non-community water system with insufficient 
tier 1 sites that meet the targeting criteria in paragraph (a)(6) of 
this section shall complete its sampling pool with sampling sites that 
contain copper pipes with lead solder installed before 1983. If 
additional sites are needed to complete

[[Page 479]]

the sampling pool, the non-transient non-community water system shall 
use representative sites throughout the distribution system. For the 
purpose of this paragraph, a representative site is a site in which the 
plumbing materials used at that site would be commonly found at other 
sites served by the water system.
    (8) Any water system whose distribution system contains lead service 
lines shall draw 50 percent of the samples it collects during each 
monitoring period from sites that contain lead pipes, or copper pipes 
with lead solder, and 50 percent of the samples from sites served by a 
lead service line. A water system that cannot identify a sufficient 
number of sampling sites served by a lead service line shall collect 
first-draw samples from all of the sites identified as being served by 
such lines.
    (b) Sample collection methods. (1) All tap samples for lead and 
copper collected in accordance with this subpart, with the exception of 
lead service line samples collected under Sec. 141.84(c) and samples 
collected under paragraph (b)(5) of this section, shall be first-draw 
samples.
    (2) Each first-draw tap sample for lead and copper shall be one 
liter in volume and have stood motionless in the plumbing system of each 
sampling site for at least six hours. First-draw samples from 
residential housing shall be collected from the cold water kitchen tap 
or bathroom sink tap. First-draw samples from a nonresidential building 
shall be one liter in volume and shall be collected at an interior tap 
from which water is typically drawn for consumption. Non-first-draw 
samples collected in lieu of first-draw samples pursuant to paragraph 
(b)(5) of this section shall be one liter in volume and shall be 
collected at an interior tap from which water is typically drawn for 
consumption. First-draw samples may be collected by the system or the 
system may allow residents to collect first-draw samples after 
instructing the residents of the sampling procedures specified in this 
paragraph. To avoid problems of residents handling nitric acid, 
acidification of first-draw samples may be done up to 14 days after the 
sample is collected. After acidification to resolubilize the metals, the 
sample must stand in the original container for the time specified in 
the approved EPA method before the sample can be analyzed. If a system 
allows residents to perform sampling, the system may not challenge, 
based on alleged errors in sample collection, the accuracy of sampling 
results.
    (3) Each service line sample shall be one liter in volume and have 
stood motionless in the lead service line for at least six hours. Lead 
service line samples shall be collected in one of the following three 
ways:
    (i) At the tap after flushing the volume of water between the tap 
and the lead service line. The volume of water shall be calculated based 
on the interior diameter and length of the pipe between the tap and the 
lead service line;
    (ii) Tapping directly into the lead service line; or
    (iii) If the sampling site is a building constructed as a single-
family residence, allowing the water to run until there is a significant 
change in temperature which would be indicative of water that has been 
standing in the lead service line.
    (4) A water system shall collect each first draw tap sample from the 
same sampling site from which it collected a previous sample. If, for 
any reason, the water system cannot gain entry to a sampling site in 
order to collect a follow-up tap sample, the system may collect the 
follow-up tap sample from another sampling site in its sampling pool as 
long as the new site meets the same targeting criteria, and is within 
reasonable proximity of the original site.
    (5) A non-transient non-community water system, or a community water 
system that meets the criteria of Sec. Sec. 141.85(c)(7)(i) and (ii), 
that does not have enough taps that can supply first-draw samples, as 
defined in Sec. 141.2, may apply to the State in writing to substitute 
non-first-draw samples. Such systems must collect as many first-draw 
samples from appropriate taps as possible and identify sampling times 
and locations that would likely result in the longest standing time for 
the remaining sites. The State has the discretion to waive the 
requirement for prior State approval of non-first-draw

[[Page 480]]

sample sites selected by the system, either through State regulation or 
written notification to the system.
    (c) Number of samples. Water systems shall collect at least one 
sample during each monitoring period specified in paragraph (d) of this 
section from the number of sites listed in the first column (``standard 
monitoring'') of the table in this paragraph. A system conducting 
reduced monitoring under paragraph (d)(4) of this section shall collect 
at least one sample from the number of sites specified in the second 
column (``reduced monitoring'') of the table in this paragraph during 
each monitoring period specified in paragraph (d)(4) of this section. 
Such reduced monitoring sites shall be representative of the sites 
required for standard monitoring. States may specify sampling locations 
when a system is conducting reduced monitoring. The table is as follows:

------------------------------------------------------------------------
                                                 Number of    Number of
                                                   sites        sites
     System size (number of people served)       (standard     (reduced
                                                monitoring)  monitoring)
------------------------------------------------------------------------
100,000............................        100           50
10,001 to 100,000.............................         60           30
3,301 to 10,000...............................         40           20
501 to 3,300..................................         20           10
101 to 500....................................         10            5
<=100.........................................          5            5
------------------------------------------------------------------------

    (d) Timing of monitoring--(1) Initial tap sampling.
    The first six-month monitoring period for small, medium-size and 
large systems shall begin on the following dates:

------------------------------------------------------------------------
                                           First six-month monitoring
    System size (No. people served)             period begins on
------------------------------------------------------------------------
50,000.....................  January 1, 1992.
3,301 to 50,000.......................  July 1, 1992.
<=3,300...............................  July 1, 1993.
------------------------------------------------------------------------

    (i) All large systems shall monitor during two consecutive six-month 
periods.
    (ii) All small and medium-size systems shall monitor during each 
six-month monitoring period until:
    (A) The system exceeds the lead or copper action level and is 
therefore required to implement the corrosion control treatment 
requirements under Sec. 141.81, in which case the system shall continue 
monitoring in accordance with paragraph (d)(2) of this section, or
    (B) The system meets the lead and copper action levels during two 
consecutive six-month monitoring periods, in which case the system may 
reduce monitoring in accordance with paragraph (d)(4) of this section.
    (2) Monitoring after installation of corrosion control and source 
water treatment. (i) Any large system which installs optimal corrosion 
control treatment pursuant to Sec. 141.81(d)(4) shall monitor during 
two consecutive six-month monitoring periods by the date specified in 
Sec. 141.81(d)(5).
    (ii) Any small or medium-size system which installs optimal 
corrosion control treatment pursuant to Sec. 141.81(e)(5) shall monitor 
during two consecutive six-month monitoring periods by the date 
specified in Sec. 141.81(e)(6).
    (iii) Any system which installs source water treatment pursuant to 
Sec. 141.83(a)(3) shall monitor during two consecutive six-month 
monitoring periods by the date specified in Sec. 141.83(a)(4).
    (3) Monitoring after State specifies water quality parameter values 
for optimal corrosion control. After the State specifies the values for 
water quality control parameters under Sec. 141.82(f), the system shall 
monitor during each subsequent six-month monitoring period, with the 
first monitoring period to begin on the date the State specifies the 
optimal values under Sec. 141.82(f).
    (4) Reduced monitoring. (i) A small or medium-size water system that 
meets the lead and copper action levels during each of two consecutive 
six-month monitoring periods may reduce the number of samples in 
accordance with paragraph (c) of this section, and reduce the frequency 
of sampling to once per year.
    (ii) Any water system that maintains the range of values for the 
water quality control parameters reflecting optimal corrosion control 
treatment specified by the State under Sec. 141.82(f) during each of 
two consecutive six-month monitoring periods may reduce the frequency of 
monitoring to once per year and reduce the number of lead and copper 
samples in accordance with paragraph (c) of this section if it receives 
written approval from the State. The

[[Page 481]]

State shall review monitoring, treatment, and other relevant information 
submitted by the water system in accordance with Sec. 141.90, and shall 
notify the system in writing when it determines the system is eligible 
to commence reduced monitoring pursuant to this paragraph. The State 
shall review, and where appropriate, revise its determination when the 
system submits new monitoring or treatment data, or when other data 
relevant to the number and frequency of tap sampling becomes available.
    (iii) A small or medium-size water system that meets the lead and 
copper action levels during three consecutive years of monitoring may 
reduce the frequency of monitoring for lead and copper from annually to 
once every three years. Any water system that maintains the range of 
values for the water quality control parameters reflecting optimal 
corrosion control treatment specified by the State under Sec. 141.82(f) 
during three consecutive years of monitoring may reduce the frequency of 
monitoring from annually to once every three years if it receives 
written approval from the State. The State shall review monitoring, 
treatment, and other relevant information submitted by the water system 
in accordance with Sec. 141.90, and shall notify the system in writing 
when it determines the system is eligible to reduce the frequency of 
monitoring to once every three years. The State shall review, and where 
appropriate, revise its determination when the system submits new 
monitoring or treatment data, or when other data relevant to the number 
and frequency of tap sampling becomes available.
    (iv) A water system that reduces the number and frequency of 
sampling shall collect these samples from representative sites included 
in the pool of targeted sampling sites identified in paragraph (a) of 
this section. Systems sampling annually or less frequently shall conduct 
the lead and copper tap sampling during the months of June, July, 
August, or September unless the State has approved a different sampling 
period in accordance with paragraph (d)(4)(iv)(A) of this section.
    (A) The State, at its discretion, may approve a different period for 
conducting the lead and copper tap sampling for systems collecting a 
reduced number of samples. Such a period shall be no longer than four 
consecutive months and must represent a time of normal operation where 
the highest levels of lead are most likely to occur. For a non-transient 
non-community water system that does not operate during the months of 
June through September, and for which the period of normal operation 
where the highest levels of lead are most likely to occur is not known, 
the State shall designate a period that represents a time of normal 
operation for the system.
    (B) Systems monitoring annually, that have been collecting samples 
during the months of June through September and that receive State 
approval to alter their sample collection period under paragraph 
(d)(4)(iv)(A) of this section, must collect their next round of samples 
during a time period that ends no later than 21 months after the 
previous round of sampling. Systems monitoring triennially that have 
been collecting samples during the months of June through September, and 
receive State approval to alter the sampling collection period as per 
paragraph (d)(4)(iv)(A) of this section, must collect their next round 
of samples during a time period that ends no later than 45 months after 
the previous round of sampling. Subsequent rounds of sampling must be 
collected annually or triennially, as required by this section. Small 
systems with waivers, granted pursuant to paragraph (g) of this section, 
that have been collecting samples during the months of June through 
September and receive State approval to alter their sample collection 
period under paragraph (d)(4)(iv)(A) of this section must collect their 
next round of samples before the end of the 9-year period.
    (v) Any water system that demonstrates for two consecutive 6-month 
monitoring periods that the tap water lead level computed under Sec. 
141.80(c)(3) is less than or equal to 0.005 mg/L and the tap water 
copper level computed under Sec. 141.80(c)(3) is less than or equal to 
0.65 mg/L may reduce the number of samples in accordance with paragraph

[[Page 482]]

(c) of this section and reduce the frequency of sampling to once every 
three calendar years.
    (vi)(A) A small or medium-size water system subject to reduced 
monitoring that exceeds the lead or copper action level shall resume 
sampling in accordance with paragraph (d)(3) of this section and collect 
the number of samples specified for standard monitoring under paragraph 
(c) of this section. Such a system shall also conduct water quality 
parameter monitoring in accordance with Sec. 141.87(b), (c) or (d) (as 
appropriate) during the monitoring period in which it exceeded the 
action level. Any such system may resume annual monitoring for lead and 
copper at the tap at the reduced number of sites specified in paragraph 
(c) of this section after it has completed two subsequent consecutive 
six-month rounds of monitoring that meet the criteria of paragraph 
(d)(4)(i) of this section and/or may resume triennial monitoring for 
lead and copper at the reduced number of sites after it demonstrates 
through subsequent rounds of monitoring that it meets the criteria of 
either paragraph (d)(4)(iii) or (d)(4)(v) of this section.
    (B) Any water system subject to the reduced monitoring frequency 
that fails to operate at or above the minimum value or within the range 
of values for the water quality parameters specified by the State under 
Sec. 141.82(f) for more than nine days in any six-month period 
specified in Sec. 141.87(d) shall conduct tap water sampling for lead 
and copper at the frequency specified in paragraph (d)(3) of this 
section, collect the number of samples specified for standard monitoring 
under paragraph (c) of this section, and shall resume monitoring for 
water quality parameters within the distribution system in accordance 
with Sec. 141.87(d). Such a system may resume reduced monitoring for 
lead and copper at the tap and for water quality parameters within the 
distribution system under the following conditions:
    (1) The system may resume annual monitoring for lead and copper at 
the tap at the reduced number of sites specified in paragraph (c) of 
this section after it has completed two subsequent six-month rounds of 
monitoring that meet the criteria of paragraph (d)(4)(ii) of this 
section and the system has received written approval from the State that 
it is appropriate to resume reduced monitoring on an annual frequency.
    (2) The system may resume triennial monitoring for lead and copper 
at the tap at the reduced number of sites after it demonstrates through 
subsequent rounds of monitoring that it meets the criteria of either 
paragraph (d)(4)(iii) or (d)(4)(v) of this section and the system has 
received written approval from the State that it is appropriate to 
resume triennial monitoring.
    (3) The system may reduce the number of water quality parameter tap 
water samples required in accordance with Sec. 141.87(e)(1) and the 
frequency with which it collects such samples in accordance with Sec. 
141.87(e)(2). Such a system may not resume triennial monitoring for 
water quality parameters at the tap until it demonstrates, in accordance 
with the requirements of Sec. 141.87(e)(2), that it has re-qualified 
for triennial monitoring.
    (vii) Any water system subject to a reduced monitoring frequency 
under paragraph (d)(4) of this section that either adds a new source of 
water or changes any water treatment shall inform the State in writing 
in accordance with Sec. 141.90(a)(3). The State may require the system 
to resume sampling in accordance with paragraph (d)(3) of this section 
and collect the number of samples specified for standard monitoring 
under paragraph (c) of this section or take other appropriate steps such 
as increased water quality parameter monitoring or re-evaluation of its 
corrosion control treatment given the potentially different water 
quality considerations.
    (e) Additional monitoring by systems. The results of any monitoring 
conducted in addition to the minimum requirements of this section shall 
be considered by the system and the State in making any determinations 
(i.e., calculating the 90th percentile lead or copper level) under this 
subpart.
    (f) Invalidation of lead or copper tap water samples. A sample 
invalidated under this paragraph does not count toward determining lead 
or copper 90th percentile levels under Sec. 141.80(c)(3) or

[[Page 483]]

toward meeting the minimum monitoring requirements of paragraph (c) of 
this section.
    (1) The State may invalidate a lead or copper tap water sample at 
least if one of the following conditions is met.
    (i) The laboratory establishes that improper sample analysis caused 
erroneous results.
    (ii) The State determines that the sample was taken from a site that 
did not meet the site selection criteria of this section.
    (iii) The sample container was damaged in transit.
    (iv) There is substantial reason to believe that the sample was 
subject to tampering.
    (2) The system must report the results of all samples to the State 
and all supporting documentation for samples the system believes should 
be invalidated.
    (3) To invalidate a sample under paragraph (f)(1) of this section, 
the decision and the rationale for the decision must be documented in 
writing. States may not invalidate a sample solely on the grounds that a 
follow-up sample result is higher or lower than that of the original 
sample.
    (4) The water system must collect replacement samples for any 
samples invalidated under this section if, after the invalidation of one 
or more samples, the system has too few samples to meet the minimum 
requirements of paragraph (c) of this section. Any such replacement 
samples must be taken as soon as possible, but no later than 20 days 
after the date the State invalidates the sample or by the end of the 
applicable monitoring period, whichever occurs later. Replacement 
samples taken after the end of the applicable monitoring period shall 
not also be used to meet the monitoring requirements of a subsequent 
monitoring period. The replacement samples shall be taken at the same 
locations as the invalidated samples or, if that is not possible, at 
locations other than those already used for sampling during the 
monitoring period.
    (g) Monitoring waivers for small systems. Any small system that 
meets the criteria of this paragraph may apply to the State to reduce 
the frequency of monitoring for lead and copper under this section to 
once every nine years (i.e., a ``full waiver'') if it meets all of the 
materials criteria specified in paragraph (g)(1) of this section and all 
of the monitoring criteria specified in paragraph (g)(2) of this 
section. If State regulations permit, any small system that meets the 
criteria in paragraphs (g)(1) and (2) of this section only for lead, or 
only for copper, may apply to the State for a waiver to reduce the 
frequency of tap water monitoring to once every nine years for that 
contaminant only (i.e., a ``partial waiver'').
    (1) Materials criteria. The system must demonstrate that its 
distribution system and service lines and all drinking water supply 
plumbing, including plumbing conveying drinking water within all 
residences and buildings connected to the system, are free of lead-
containing materials and/or copper-containing materials, as those terms 
are defined in this paragraph, as follows:
    (i) Lead. To qualify for a full waiver, or a waiver of the tap water 
monitoring requirements for lead (i.e., a ``lead waiver''), the water 
system must provide certification and supporting documentation to the 
State that the system is free of all lead-containing materials, as 
follows:
    (A) It contains no plastic pipes which contain lead plasticizers, or 
plastic service lines which contain lead plasticizers; and
    (B) It is free of lead service lines, lead pipes, lead soldered pipe 
joints, and leaded brass or bronze alloy fittings and fixtures, unless 
such fittings and fixtures meet the specifications of any standard 
established pursuant to 42 U.S.C. 300g-6(e) (SDWA section 1417(e)).
    (ii) Copper. To qualify for a full waiver, or a waiver of the tap 
water monitoring requirements for copper (i.e., a ``copper waiver''), 
the water system must provide certification and supporting documentation 
to the State that the system contains no copper pipes or copper service 
lines.
    (2) Monitoring criteria for waiver issuance. The system must have 
completed at least one 6-month round of standard tap water monitoring 
for lead and copper at sites approved by the State and from the number 
of sites required by paragraph (c) of this section

[[Page 484]]

and demonstrate that the 90th percentile levels for any and all rounds 
of monitoring conducted since the system became free of all lead-
containing and/or copper-containing materials, as appropriate, meet the 
following criteria.
    (i) Lead levels. To qualify for a full waiver, or a lead waiver, the 
system must demonstrate that the 90th percentile lead level does not 
exceed 0.005 mg/L.
    (ii) Copper levels. To qualify for a full waiver, or a copper 
waiver, the system must demonstrate that the 90th percentile copper 
level does not exceed 0.65 mg/L.
    (3) State approval of waiver application. The State shall notify the 
system of its waiver determination, in writing, setting forth the basis 
of its decision and any condition of the waiver. As a condition of the 
waiver, the State may require the system to perform specific activities 
(e.g., limited monitoring, periodic outreach to customers to remind them 
to avoid installation of materials that might void the waiver) to avoid 
the risk of lead or copper concentration of concern in tap water. The 
small system must continue monitoring for lead and copper at the tap as 
required by paragraphs (d)(1) through (d)(4) of this section, as 
appropriate, until it receives written notification from the State that 
the waiver has been approved.
    (4) Monitoring frequency for systems with waivers. (i) A system with 
a full waiver must conduct tap water monitoring for lead and copper in 
accordance with paragraph (d)(4)(iv) of this section at the reduced 
number of sampling sites identified in paragraph (c) of this section at 
least once every nine years and provide the materials certification 
specified in paragraph (g)(1) of this section for both lead and copper 
to the State along with the monitoring results.
    (ii) A system with a partial waiver must conduct tap water 
monitoring for the waived contaminant in accordance with paragraph 
(d)(4)(iv) of this section at the reduced number of sampling sites 
specified in paragraph (c) of this section at least once every nine 
years and provide the materials certification specified in paragraph 
(g)(1) of this section pertaining to the waived contaminant along with 
the monitoring results. Such a system also must continue to monitor for 
the non-waived contaminant in accordance with requirements of paragraph 
(d)(1) through (d)(4) of this section, as appropriate.
    (iii) If a system with a full or partial waiver adds a new source of 
water or changes any water treatment, the system must notify the State 
in writing in accordance with Sec. 141.90(a)(3). The State has the 
authority to require the system to add or modify waiver conditions 
(e.g., require recertification that the system is free of lead-
containing and/or copper-containing materials, require additional 
round(s) of monitoring), if it deems such modifications are necessary to 
address treatment or source water changes at the system.
    (iv) If a system with a full or partial waiver becomes aware that it 
is no longer free of lead-containing or copper-containing materials, as 
appropriate, (e.g., as a result of new construction or repairs), the 
system shall notify the State in writing no later than 60 days after 
becoming aware of such a change.
    (5) Continued eligibility. If the system continues to satisfy the 
requirements of paragraph (g)(4) of this section, the waiver will be 
renewed automatically, unless any of the conditions listed in paragraph 
(g)(5)(i) through (g)(5)(iii) of this section occurs. A system whose 
waiver has been revoked may re-apply for a waiver at such time as it 
again meets the appropriate materials and monitoring criteria of 
paragraphs (g)(1) and (g)(2) of this section.
    (i) A system with a full waiver or a lead waiver no longer satisfies 
the materials criteria of paragraph (g)(1)(i) of this section or has a 
90th percentile lead level greater than 0.005 mg/L.
    (ii) A system with a full waiver or a copper waiver no longer 
satisfies the materials criteria of paragraph (g)(1)(ii) of this section 
or has a 90th percentile copper level greater than 0.65 mg/L.
    (iii) The State notifies the system, in writing, that the waiver has 
been revoked, setting forth the basis of its decision.
    (6) Requirements following waiver revocation. A system whose full or 
partial waiver has been revoked by the State

[[Page 485]]

is subject to the corrosion control treatment and lead and copper tap 
water monitoring requirements, as follows:
    (i) If the system exceeds the lead and/or copper action level, the 
system must implement corrosion control treatment in accordance with the 
deadlines specified in Sec. 141.81(e), and any other applicable 
requirements of this subpart.
    (ii) If the system meets both the lead and the copper action level, 
the system must monitor for lead and copper at the tap no less 
frequently than once every three years using the reduced number of 
sample sites specified in paragraph (c) of this section.
    (7) Pre-existing waivers. Small system waivers approved by the State 
in writing prior to April 11, 2000 shall remain in effect under the 
following conditions:
    (i) If the system has demonstrated that it is both free of lead-
containing and copper-containing materials, as required by paragraph 
(g)(1) of this section and that its 90th percentile lead levels and 90th 
percentile copper levels meet the criteria of paragraph (g)(2) of this 
section, the waiver remains in effect so long as the system continues to 
meet the waiver eligibility criteria of paragraph (g)(5) of this 
section. The first round of tap water monitoring conducted pursuant to 
paragraph (g)(4) of this section shall be completed no later than nine 
years after the last time the system has monitored for lead and copper 
at the tap.
    (ii) If the system has met the materials criteria of paragraph 
(g)(1) of this section but has not met the monitoring criteria of 
paragraph (g)(2) of this section, the system shall conduct a round of 
monitoring for lead and copper at the tap demonstrating that it meets 
the criteria of paragraph (g)(2) of this section no later than September 
30, 2000. Thereafter, the waiver shall remain in effect as long as the 
system meets the continued eligibility criteria of paragraph (g)(5) of 
this section. The first round of tap water monitoring conducted pursuant 
to paragraph (g)(4) of this section shall be completed no later than 
nine years after the round of monitoring conducted pursuant to paragraph 
(g)(2) of this section.

[56 FR 26548, June 7, 1991; 56 FR 32113, July 15, 1991; 57 FR 28788, 
June 29, 1992; as amended at 65 FR 2007, Jan. 12, 2000]