LEAD AND COPPER RULE
Overview
Purpose
The purpose of the lead and copper rule is to protect public health by minimizing lead and copper levels in drinking
water, primarily by reducing water corrosivity. Most regulations require sampling at entry points to the distribution
system. Because lead and copper in drinking water is mainly due to the corrosion of service lines and household
plumbing materials, tap water samples are collected at kitchen or bathroom taps of residences and other buildings.
Public Health Benefits
Implementation of the lead and copper rule has resulted in:
 Reduction in risk of exposure to lead that can cause damage to the brain, red blood cells and kidneys, especially for
young children and pregnant women; and
 Reduction in risk of exposure to copper that can cause stomach and intestinal distress, liver and kidney damage.
Affected System
Lead and copper tap monitoring applies to all community water systems (CWSs) and non-transient non-community
water systems (NTNCWs).
Requirements
Systems are required to take tap water samples in the distribution system to test for lead and copper. The number of
required tap water samples is based on the size of the system and the monitoring plan. Systems are required to notify
the state and sample site residents of these results. These tap water monitoring results are the primary factor for
determining a systems ongoing monitoring requirements and whether they need to undertake any of the following
treatment technique requirements:
 Corrosion control treatment;
 Source Water Treatment;
 Public education; and/or
 Lead service line replacement.
There is no maximum contaminant level (MCL) for lead or copper. However, if your lead and copper tap 90 th percentile
monitoring results are higher than the lead action level of 0.015 milligrams per liter (mg/L) and/or the copper action
level of 1.3 mg/L, corrosion control treatment is required.
If your 90th percentile level exceeds the lead action level of 0.015 mg/L, you must:
 Conduct corrosion control treatment steps, which include water quality parameter (WQP) monitoring during the
same monitoring period in which the exceedance occurs;
 Conduct source water monitoring at entry points to the distribution system, make a treatment recommendation,
and install source water treatment, if needed;
 Deliver public education that informs your users about the health effects of lead, measures that will reduce their
exposure to lead, and sources of additional information; and
 Replace lead service lines if you still exceed the lead action level after installing treatment.
If your 90th percentile level exceeds the copper action level of 1.3 mg/L, you must:
 Conduct corrosion control treatment steps which include WQP monitoring during the same monitoring period in
which the exceedance occurs; and
 Conduct source water monitoring, make treatment recommendations, and install source water treatment if needed.
Monitoring Requirements
Standard Monitoring
Standard monitoring encompasses all monitoring other than reduced monitoring and is conducted at six-month
intervals. Both initial monitoring (required for all systems) and follow-up monitoring (corresponds to the two
consecutive six-months after a system completes the installation of corrosion control and is only required for systems
that install treatment) are a type of standard monitoring. Systems on standard monitoring require a larger number of
minimum samples.
System Size
> 100,000
10,001 – 100,000
3,301 – 10,000
501 – 3,300
101 – 500
≤ 100
Minimum Number of Samples for Standard Monitoring
100
60
40
20
10
5
Initial Monitoring
If a system serves more than 50,000 people, they are required to conduct two six-month rounds of initial lead and
copper tap water monitoring at the standard number of sites based on the system size.
If a system serves less than 50,000 people, they are required to conduct a minimum of one, six-month round of initial
monitoring at the standards number of sites. The requirement to conduct a second round of initial monitoring is based
on the 90th percentile during the first round of monitoring:
 Systems are not required to collect a second round of initial monitoring if the lead or copper action level is
exceeded. Instead, corrosion control treatment steps are triggered.
 Systems are required to conduct a second round of initial monitoring during the next 6 months if they were at or
below the lead and copper action levels during the first round of monitoring.
Follow-up Monitoring
If a system is required to install corrosion control treatment, they must conduct two consecutive six-month rounds of
follow-up monitoring at the standard number of sites. If the system serves 50,000 or fewer people, this monitoring must
be completed within one year of installing corrosion control treatment.
Reduced Monitoring
Reduced monitoring corresponds to monitoring that occurs at a reduced frequency and a reduced number of sample
locations.
System Size
> 100,000
10,001 – 100,000
3,301 – 10,000
501 – 3,300
101 – 500
≤ 100
Minimum Number of Samples for Reduced Monitoring
50
30
20
10
5
5
Annual Monitoring Criteria
A system can reduce the frequency of their monitoring to annually beginning in the calendar year immediately following
the end of the second consecutive six-month monitoring period and collect from a reduced number of sites if the system
is at or below both action levels during two consecutive six-month monitoring periods.
Triennial Monitoring Criteria
A system can reduce the frequency of sampling to once every three years and collect the reduced number of samples if
they meet any of the following criteria:
 Its 90th percentile lead and copper levels are at or below both action levels for three consecutive years. Two
consecutive six-month periods at or below both action levels (such as the two initial monitoring periods) can count
as the first year of the three years needed to qualify for triennial monitoring; or
 Its 90th percentile lead levels of less than or equal to 0.005 mg/L and 90th percentile copper levels of less than or
equal to 0.65 mg/L, for two consecutive periods (also known as accelerated reduced lead and copper tap
monitoring).
When to Sample on Reduced Monitoring
For a system that is on reduced lead and copper tap monitoring (i.e., annual, triennial, or nine-year monitoring), samples
must be conducted during the summer months of June through September because these are the months in which the
highest lead levels are expected to occur.
 For systems that qualify for annual monitoring, the first year of annual monitoring begins during the calendar year
immediately following the end of the second consecutive six-month monitoring period in which it met the criteria
for annual monitoring.
 For systems that qualify for triennial monitoring, the first year of triennial monitoring begins the third calendar year
immediately following the end of the third consecutive year of monitoring in which it met the criteria for triennial
monitoring.
Sample Site Requirements
Sample sites are classified using a tier classification system. The tier level is determined by the type of water system, the
type of residence and the type of plumbing. The following graph depicts the tier classification for community water
system and non-transient non-community water systems.
COMMUNITY WATER SYSTEM
Tier
Single Family Residence
Multiple Family Residence/ Buildings
- Copper pipes w/ lead solder
installed AFTER 1982
1
- Lead Pipes
- Lead service lines
- Copper pipes w/ lead solder
installed AFTER 1982
2
- Lead Pipes
- Lead service lines
- Copper pipes with lead solder
3
installed BEFORE 1983
- Copper pipes with lead solder
Non-Tier
- Non-copper and non-lead
installed BEFORE 1983
- Non-copper and non-lead
NON-TRANSIENT NON-COMMUNITY WATER SYSTEMS
Tier
1
- Copper pipes w/ lead solder installed AFTER 1982
- Lead Pipes
- Lead service lines
2
- Copper pipes with lead solder installed BEFORE 1983
3
Non-Tier
- Non-copper and non-lead




The first-draw lead and copper samples must be collected from tier 1 sites. (Note: For those systems that have lead
service lines, 50% of the samples must be collected from sites with lead service lines).
If there are not a sufficient number of tier 1 sampling sites available, then a system may complete its sampling pool
with tier 2 sites. If there are not a sufficient number of tier 1 and tier 2 sampling sites available, then a system may
complete its sampling pool with tier 3 sites.
Any water system that cannot complete its sampling at sites that meet the applicable tier criteria must complete
sampling at representative sites throughout the distribution system. These sites must have plumbing similar to that
used at other sites served by the water system.
Samples should be collected from an indoor kitchen or bathroom sink that is used on a daily basis. Samples should
not be collected from outside spigots, water fountains, or sites with a treatment device or an additional form of
water treatment.
Sample Results
Lead and copper analytical results are evaluated against an action level, not an MCL. The lead action level is exceeded if
the concentration of lead in more than 10 percent of tap water samples collected during any monitoring period is
greater than 0.015 mg/L (i.e., if the 90th percentile lead level is greater than 0.015 mg/L). The copper action level is
exceeded if the concentration of copper in more than 10 percent of tap water samples collected during any monitoring
period conducted is greater than 1.3 mg/L (i.e., if the 90th percentile copper level is greater than 1.3 mg/L). The 90th
percentile is calculated separately for lead and copper.
Systems Collecting More Than Five Samples
Step 1: Place lead/copper results in ascending order (from lowest to highest value).
Step 2: Assign each sample a number, 1 for lowest value.
Step 3: Multiply the total number of samples by 0.9.
Step 4: Compare the 90th percentile level to the action level. If the 90th percentile value is higher than the action level,
there is an exceedance.
Example
Sample Results: 0.020, 0.010, 0.006, 0.005, 0.000, 0.015, 0.006, 0.005, 0.002, 0.000
Step 1: 0.000, 0.000, 0.002, 0.005, 0.005, 0.006, 0.006, 0.010, 0.015, 0.020
Step 2:
1
2
3
4
5
6
7
8
9
10
0.000, 0.000, 0.002, 0.005, 0.005, 0.006, 0.006, 0.010, 0.012, 0.020
Step 3: 10 x 0.9 = 9* (corresponds to sample #9)
If this is not a whole number, round to the nearest whole number. Round down to the nearest whole number if the
decimal is 0.4 or less and round up to the nearest whole number if the decimal is 0.5 or higher.
Step 4: Sample #9 is 0.012 < 0.015
Systems Collecting Less Than Five Samples
Step 1: Place lead/copper results in ascending order (from lowest to highest value).
Step 2: Take the average of the 4th and 5th highest sample. This is the 90th percentile level.
Step 3: Compare the 90th percentile level to the action level. If the 90th percentile value is higher than the action level,
there is an exceedance.
Example
Sample Results: 0.008, 0.006, 0.020, 0.000, 0.001
Step 1: 0.000, 0.001, 0.006, 0.008, 0.020
Step 2: (0.008 + 0.020)/2 = 0.014
Step 3: 0.014 <0.015