UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WSG 174
Date Signed: November 23, 2004
MEMORANDUM
SUBJECT: Lead and Copper Rule - Clarification of Requirements for Collecting Samples and
Calculating Compliance
FROM: Benjamin H. Grumbles
Acting Assistant Administrator
TO: Regional Administrators
Water Division Directors
Regions I- X
This memo reiterates and clarifies elements of the Lead and Copper Rule (LCR)
associated with the collection and management of lead and copper samples and the calculation of
the lead 90th percentile for compliance. Over the past several months, Headquarters has been
conducting a national review of implementation of the LCR. This review consists of both data
analysis and feedback from expert panels on aspects of the rule. Headquarters is continuing its
review, and will be making a determination in early 2005 on specific areas of the rule that may
require changes in regulation or need clarification through guidance or training.
One area identified for additional guidance is the management of lead and copper
samples and the calculation of the lead 90th percentile. Because the need for additional guidance
was identified in both Headquarters' data review and the expert panels, Headquarters is
addressing this area prior to the final determination on rule and guidance changes. This guidance
reflects the requirements of the LCR as it is currently written. These issues may be revised if
EPA makes a determination that changes should be made to the LCR.
1) What samples are used to calculate the 90th percentile?
We have received several questions regarding what tap samples should be used to
calculate the 90th percentile for lead, specifically, where utilities collect samples beyond the
minimum number required by the regulations. EPA regulations require water systems to devleop
a targeted sampling pool, focused on those sites with the greatest risk of lead leaching. All
compliance samples used to determine the 90th percentile must come from that sampling pool.
All sample results from a system's sampling pool during the monitoring period must be included
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in the 90th percentile calculation, even if this includes more samples than the required minimum
number needed for compliance. [40 CFR 141.86(e)] For example, consider a situation where a
system sends out sample kits to 150 households to ensure that it will have a sufficient number of
samples to meet its required 100 samples for compliance. If the system receives sample results
from 140 households, it would use the results of the 140 samples in calculating the 90th
percentile.
In some cases, a utility may choose to
take a confirmation sample to verify high or low
concentration. It is entirely possible for the
concentration of a confirmation sample to be
significantly higher or lower than the
concentration of the original sample. However,
where confirmation samples are taken, the
results of the original and confirmation sample
must be used in calculating the 90th percentile.
The LCR does not allow substitution of results
with "confirmation" samples, nor does it allow
the averaging of initial and confirmation
samples as a single sampling result. While we
support re-sampling at a home with high lead
levels, all sample results from the sampling pool
collected within the monitoring period must be
included in the calculation.
Inclusion of samples in
90th Percentile Calculations
40 CFR 141.86(e) "The results of any additional
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."
40 CFR 141.80(c)(3)(i) "The results of all lead and
copper samples taken during a monitoring period
shall be placed in ascending order from the sample
with the lowest concentration to the sample with the
highest concentration..." [emphasis added]
2) What should utilities do with sample results from customer-requested sampling
programs?
EPA regulations require water systems to develop a targeted sampling pool, focused on
those sites with the greatest risk of lead leaching. All compliance samples used to determine the
90th percentile must come from that sampling pool. [40 CFR 141.80(c)(l)] ("Samples collected at
sites not meeting the targeting criteria may not be used in calculating the 90th percentile lead and
copper levels." 56 Fed Reg. 26518 (June 7, 1991)). Maintaining a consistent set of compliance
sample sites provides the system with a baseline against which to measure the 90th percentile
over time. If a system designates sites which were not sampled during previous monitoring
periods, it must notify the state and include an explanation of why the sampling sites have
changed. [40 CFR 141.90(a)(l)(v) and 141.90(h)(2)]
In addition to compliance sampling, many water systems have additional programs to test
for lead in drinking water at the request of homeowners. Customer-requested samples that are
not collected as part of the system's regular compliance sampling pool may or may not meet the
sample site selection criteria, and the system may not have sufficient information to determine
whether they do or not. Including results from samples that do not meet the criteria could
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inappropriately reduce the 90th percentile value. Therefore, samples collected under these
programs should not be used to calculate the 90th percentile, except in cases where the system is
reasonably able to determine that the site selection criteria for compliance sampling is satisfied.
However, even though these customer-requested samples are not used for the 90th
percentile calculation, the sample results must still be provided to the state. [40 CFR 141.90(g)]
If a significant number of customer-requested samples are above the lead action level, the state
should re-evaluate the corrosion control used by the system and the composition of the
compliance sampling pool. Further, where any results are above the action level, we strongly
urge systems to follow up with the affected customers to provide them with information on ways
to reduce their risk of exposure to elevated lead levels in drinking water.
3) What should states do with samples taken outside of the sampling compliance
period?
The regulations require that systems on reduced monitoring collect samples during the
period between June and September, unless the state had approved an alternate period. [40 CFR
141.86(d)(4)(iv)] Only those samples collected during the compliance monitoring period may be
included in the 90th percentile calculation. [40 CFR 141.80(c)(3)]
An exception to this is where a state invalidates a sample and the system must collect a
replacement sample in order to have sufficient number with which to calculate compliance. The
system must collect its replacement sample within 20 days of the invalidation. Even if the date
of collection occurs after the closure of the monitoring period (but within 20 days of the
invalidation), the results must be included in the 90th percentile calculation. [40 CFR
141.86(f)(4)]
Although samples collected outside the sampling compliance period should not be used
in the compliance calculation, they must still be provided to the state [40 CFR 141.90(g)], as is
the case with customer-requested samples.
4) What should states do to calculate compliance if the minimum number of samples
are not collected?
As noted in guidance released earlier this year1, states must calculate the 90th percentile
even if the minimum number of samples are not collected. The LCR states that the 90th
percentile level is calculated based on "all samples taken during a monitoring period" and does
not require that the minimum required number of samples must be collected in order to calculate
the 90th percentile level. [40 CFR 141.80(c)]
1 See March 9, 2004 memorandum from Cynthia Dougherty to Jane Downing at
http://www.eap.gov/safewater/lcrmr/pdfs/memo_lcmr_lead_compliance_calculation.pdf
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A system which fails to collect the minimum
required number of samples incurs a
monitoring and reporting violation and is
thus required to conduct Tier 3 Public
Notification (PN) [40 CFR 141.204(a)] and
report the violation in its Consumer
Confidence Report (CCR) [40 CFR
141.153(f)(l)]. The system will return to
compliance for the monitoring and reporting
violation when it completes these tasks and
had completed appropriate monitoring and
reporting for two consecutive 6-month
monitoring periods (or one round of
monitoring for a system on reduced
monitoring). [State Implementation
Guidance for the LCRMR, EPA-816-R-01-
021]
5) What is a proper sample?
We have received numerous requests
to clarify the LCR with respect to proper
samples and grounds for invalidation.
The LCR was designed to ensure that samples are collected from locations which have
the highest risk of elevated lead concentrations. The rule established a tiering system
(Attachment A) that would guide utilities in selecting locations for tap sampling that are
considered high risk and requires that the sampling pool be comprised of Tier 1 sites, if they are
available. [40 CFR 141.86(a)]
The LCR also defines a proper sample as a first draw sample, 1 liter in volume, that is
taken after water has been standing in plumbing for at least six hours, and from an interior tap
typically used for consumption - cold water kitchen or bathroom sink tap in residences. [40 CFR
141.86(b)(2)] There is no outer limit on standing time.
To ensure sampling is conducted properly, the LCR requires that samples be collected by
the system or by residents if they have been properly instructed by the water system. As added
insurance that the system gives proper instructions, the rule does not allow water systems to
challenge sample results based on alleged homeowner errors in sample collection. [40 CFR
141.86(b)(2)]
Calculating the 90th Percentile
40 CFR § 141.80(c)(3) - "The 90th percentile lead and
copper levels shall be computed as follows:
(i) The results of all lead and copper samples taken
during a monitoring period shall be placed in
ascending order from the sample with the lowest
concentration to the sample with the highest
concentration. Each sampling result shall be assigned
a number, ascending by single integers beginning
with the number, ascending by single integers
beginning with the number 1 for the sample with the
lowest contaminant level. The number assigned to
the sample with the highest contaminant level shall be
equal to the total number of samples taken.
(ii) The number of samples taken during the
monitoring period shall be multiplied by 0.9.
(iii) The contaminant concentration in the numbered
sample yielded by the calculation in paragraph
(c)(3)(ii) is the 90th percentile contaminant level.
(iv) For water systems serving less than 100 people
that collect 5 samples per monitoring period, the 90th
percentile is computed by taking the average of the
highest and second highest concentrations.
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6) How can utilities avoid problems with sample collection?
In order to avoid problems with sample collection, the utility may wish to do the
sampling itself or review the sample collection information before sending it to the lab. If the
utility chooses to use residents to perform the sampling, it should provide clear instructions and a
thorough chain-of-custody form for residents to fill out when the sample is taken. This will allow
the laboratory or utility to eliminate improperly collected samples prior to the actual analysis.
For example, if a sample bottle is only half full, then it should not be analyzed by the laboratory.
Likewise, if the documentation accompanying the sample indicates that it was taken from an
outside tap, the sample should not be analyzed. Systems may need to make arrangements to
collect replacement samples for samples that are not analyzed by the laboratory.
Once a sample is analyzed, the results may not be challenged by the water system. As
explained by Question #1 of this memorandum, the results for all samples from the compliance
sampling pool must be included in the 90th percentile calculation unless there are grounds for
invalidation. Improper sampling by residents is not a grounds for invalidation under 40 CFR
141.86(f).
7) On what grounds may a sample be invalidated?
The regulations allow the state to invalidate a lead or copper tap sample only if it can
document that at least on of the following conditions has occurred:
1. The laboratory establishes that improper sample analysis caused erroneous results;
2. The state determines that the sample was taken from a site that did not meet the site
selection criteria of this section;
3. The sample container was damaged in transit; or
4. There is substantial reason to believe that the sample was subject to tampering. [40 CFR
We interpret the second condition to mean a site that is not part of the compliance
sampling pool, that has not been identified as a Tier 1 or other high risk site, or that has been
altered in such a way that it no longer meets the criteria of a high-risk site (e.g., new plumbing or
the addition of a water softener).
It is important to note that states may not invalidate a sample solely on the grounds that a
follow-up sample results is higher or lower than that of the original sample. [40 CFR
141.86(f)(3)] The system must report the results of all the samples to the state, and provide
supporting document for all samples it believes should be invalidated. [40 CFR 141.86(f)(2)]
The state must provide its formal decision on whether or not to invalidate the sample(s) in
writing. If a state makes a determination to invalidate the sample, the decision and the rationale
for the decision must be provided in writing. [40 CFR 141.86(f)(3)]
In conducting the national implementation review, we have noticed that some utilities
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may have requested invalidation of samples because they believe that there was improper
sampling on the part of the homeowner (e.g., drawing water from the incorrect tap). This is a
concern because there may be a tendency to only consider sampling errors when there are high
results, even though there could be sampling errors that would lead to artificially low results
(e.g., collecting a sample after the line was flushed). In any event. EPA takes a strict
interpretation of the invalidation requirements in the LCR. If a system allows residents to
perform sampling as part of the targeted sampling pool, the system may not challenge the
accuracy of sampling results because it believes there were errors in sample collection. [40 CFR
141.86(b)(2)] The state may only invalidate samples based on the criteria described above.
In sum, if a water system (1) sends a sample bottle to a home within its compliance
sampling pool, (2) receives the sample back from the homeowner, (3) sends the sample to the
laboratory for analysis, and (4) receives results from the analysis back from the lab; that result
must be used in calculating the 90th percentile. The only exception to this is if the state
invalidates the result in accordance with the regulation.
Conclusion
The Agency is continuing its wide-ranging review of implementation of the LCR and will
use the information to determine what changes should be made to existing guidance, training
and/or the regulatory requirements. This memo should help to provide clarification on issues
related to calculating the 90th percentile and proper management of tap samples as required under
the LCR. Please work with your states to ensure that they understand that requirements so that
they may work with the public water systems under their jurisdiction to address any
misinterpretations of the regulations. If you have additional questions or concerns, please
contact me or have your staff contact Cynthia Dougherty, Director of the Office of Ground
Water and Drinking Water at (202) 564-3750, or Ronald Bergman, Associate Chief of the
Protection Branch in the Office of Ground Water and Drinking Water, at (202) 564-3823.
Attachment
cc: Regional Drinking Water Branch Chiefs
James Taft, Association of State Drinking Water Administrators
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Attachment A
Tiering Classifications System for Selection of Monitoring Sites
Tiering Classification
If you are a Community Water System
If you are an Non-Transient
Noncommunity Water System
Tier 1 sampling sites are single family
structures: with copper pipes with lead
solder installed after 1982 (but before the
effective date of your State's lead ban) or
contain lead pipes; and/or that are served
by a lead service line.
Note: When multiple-family residences
(MFRs) comprise at least 20% of the
structures served by a water system, the
system may count them as Tier 1 sites.
Tier 2 sampling sites consist of buildings,
including MFRs: with copper pipes with
lead solder installed after 1982 (but before
effective date of your State's lead ban) or
contain lead pipes; and/or that are served
by a lead service line.
Tier 3 sampling sites are single family
structures w/ copper pipes having lead
solder installed before 1983.
Tier 1 sampling sites consist of buildings:
with copper pipes with lead solder installed
after 1982 (but before the effective date of
your State's lead ban) or contain lead
pipes; and/or
that are served by a lead service line.
Tier 2 sampling sites consist of buildings
with copper pipes with lead solder installed
before 1983.
Tier 3: Not applicable.
Note:
All States were required to ban the use of lead solder in all public water systems, and all
homes and buildings connected to such systems by June 1988 (most States adopted the
ban in 1987 or 1988). Contact the Drinking Water Program in your State to find out the
effective date.
A community water system with insufficient tier 1, tier 2 and tier 3 sampling sites, or an
non-transient noncommunity water system with insufficient tier 1 and tier 2 sites, shall
complete its sampling pool with representative sites throughout the distribution system.
For the purposes 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
systems. [40 CFR 141.86(a)(5) and (7)]
Source: Lead and Copper Monitoring and Reporting Guidance for Public Water Systems, EPA-
816-R-02-009
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