Lead and Copper Rule Fundamentals

The Lead and Copper Rule, commonly called the LCR, is a federal drinking-water regulation designed to reduce exposure to lead and copper that can enter drinking water from plumbing materials.

Unlike contaminants that are primarily present in source water, lead and copper often enter drinking water after treatment as water contacts service lines, household plumbing, solder, fixtures, and other materials.

For operators, the rule is closely connected to corrosion control, tap sampling, water-quality monitoring, service-line materials, public education, and regulatory reporting.

Where Do Lead and Copper Come From?

Lead and copper in drinking water commonly result from corrosion of plumbing materials.

Potential lead sources include:

• lead service lines;
• lead-containing solder;
• older plumbing components;
• some faucets and fixtures.

Potential copper sources include:

• copper service lines;
• copper household plumbing;
• corroding copper fittings and components.

Why Corrosion Control Matters

The Lead and Copper Rule is primarily a treatment-technique regulation.

Instead of treating lead and copper at the source-water intake, utilities often control exposure by reducing the corrosivity of finished water.

Important corrosion-control variables can include:

• pH;
• alkalinity;
• orthophosphate;
• silicate treatment;
• water age;
• chloride and sulfate conditions;
• disinfectant chemistry;
• changes in source water.

Action Levels

Lead and copper action levels are not traditional MCLs.

They are regulatory thresholds based on tap-monitoring results that can trigger additional treatment, monitoring, public education, and other requirements.

Current Lead Action Level

During the current federal transition period before the Lead and Copper Rule Improvements compliance date, the traditional lead action level remains:

15 micrograms per liter, or 15 ppb.

Current Copper Action Level

The copper action level is:

1.3 mg/L.

Action Levels Are Evaluated at the 90th Percentile

Compliance is not determined by simply averaging all lead or copper tap samples.

The traditional LCR framework uses the 90th percentile concentration.

An action level is exceeded when the 90th-percentile value is greater than the applicable action level.

What Does 90th Percentile Mean?

Tap sample results are arranged from lowest to highest.

The 90th-percentile result represents a concentration near the upper end of the sample distribution.

The exact regulatory calculation depends on the number of samples and applicable rule provisions.

Example

Suppose a system collects 20 compliance samples.

The results are ranked from lowest to highest.

The operator should follow the required regulatory method to determine the 90th-percentile value rather than calculate a simple arithmetic average.

Why Tap Sampling Is Used

Lead and copper often enter drinking water inside the distribution and premise-plumbing system.

Therefore, finished-water samples collected at the treatment plant cannot fully represent customer exposure.

The LCR requires sampling at selected customer taps.

High-Risk Sampling Sites

Compliance sampling emphasizes locations that are more likely to contain plumbing materials associated with lead exposure.

Examples can include homes with:

• lead service lines;
• lead-containing plumbing materials;
• older plumbing meeting applicable sampling-tier criteria.

First-Draw Samples

Traditional LCR tap monitoring generally uses first-draw samples collected after a period of stagnation.

The purpose is to measure water that has been in contact with premise plumbing long enough for corrosion products to accumulate.

Sampling Instructions Matter

Incorrect sampling can distort compliance results.

Operators and customers should follow approved sampling instructions.

Examples of improper practices can include:

• flushing immediately before the required stagnation period;
• collecting from the wrong faucet;
• altering the sampling procedure;
• using an inappropriate container;
• failing to document required information.

Corrosion Control Treatment

Corrosion control treatment, commonly abbreviated CCT, is a central component of the LCR.

The goal is to reduce the release of lead and copper from plumbing materials into drinking water.

Optimal Corrosion Control Treatment

When required, a system must install and operate treatment designated as optimal corrosion control treatment, or OCCT.

Examples can include:

• pH adjustment;
• alkalinity adjustment;
• orthophosphate addition;
• other approved corrosion-control strategies.

Water Quality Parameters

Systems operating corrosion control treatment can be required to monitor water quality parameters.

Depending on treatment and regulatory requirements, these can include:

• pH;
• alkalinity;
• orthophosphate;
• silica;
• calcium;
• other state-designated parameters.

Why Water Quality Parameters Matter

Water quality parameter monitoring helps demonstrate that corrosion-control treatment is operating as intended.

A system can have acceptable tap results during one period but still create future corrosion problems if treatment conditions are not maintained.

Source Water Changes Can Affect Corrosion

Changing water source, disinfectant, pH, alkalinity, or treatment process can alter pipe-scale chemistry.

Operators should evaluate major treatment or source changes for potential corrosion effects before implementation.

Lead Service Lines

Lead service lines are an important source of lead exposure.

A service line connects the water main to the building plumbing.

Depending on local ownership arrangements, portions of the service line can be owned by the utility, the property owner, or both.

Service Line Inventory

Federal requirements now require public water systems to maintain information about service-line materials.

Under requirements retained from the 2021 Lead and Copper Rule Revisions, systems were required to complete an initial service-line inventory by:

October 16, 2024.

The inventory identifies service lines by material category, including known or potential lead-related categories.

Unknown Service Lines

An unknown service-line material should not automatically be assumed to be non-lead.

Systems must continue investigating and updating service-line information according to applicable federal and state requirements.

Customer Notification

Federal requirements require notification to customers served by known or potential lead-containing service lines.

Operators should understand that service-line inventory work is connected to:

• customer communication;
• public education;
• replacement planning;
• regulatory reporting.

Public Education

When lead concentrations exceed applicable regulatory thresholds, the LCR requires public education and other communication actions.

Public education is intended to help customers reduce exposure while the water system addresses the underlying condition.

Lead Action Level Exceedance

An action level exceedance can trigger requirements such as:

• corrosion-control evaluation or treatment;
• additional monitoring;
• public education;
• public notification;
• service-line replacement requirements;
• additional reporting.

The exact response depends on system size, treatment status, service-line materials, state requirements, and the version of the federal rule currently in effect.

Lead and Copper Are Not Treated the Same

The rule regulates both lead and copper, but some requirements differ.

Lead-specific requirements can include:

• lead service-line inventories;
• lead service-line replacement;
• lead-specific public education;
• special notification requirements.

Lead and Copper Rule Improvements

EPA finalized the Lead and Copper Rule Improvements, commonly called the LCRI, in 2024.

The LCRI strengthens the federal framework for:

• lead service-line identification;
• lead service-line replacement;
• tap sampling;
• corrosion control;
• public education;
• customer notification.

Current Transition Period

Operators must distinguish current requirements from future LCRI requirements.

Selected provisions from the 2021 Lead and Copper Rule Revisions became applicable on October 16, 2024.

These retained requirements include:

• initial service-line inventories;
• notification of service-line materials;
• Tier 1 public notification following a lead action-level exceedance;
• associated reporting requirements.

LCRI Compliance Date

Most major LCRI requirements begin on:

November 1, 2027.

Until then, systems generally continue operating under the existing LCR framework except for the selected retained LCRR requirements already in effect.

Future Lead Action Level

Beginning with the LCRI compliance framework, the lead action level is reduced to:

10 micrograms per liter, or 10 ppb.

This lower value should not be confused with the 15 ppb action level used during the current transition period before the LCRI compliance date.

Copper Under the LCRI

The LCRI retains the copper action level at:

1.3 mg/L.

LCRI Tap Sampling Changes

The LCRI strengthens tap-monitoring procedures to better identify locations with elevated lead exposure.

For certain homes with lead service lines, the future sampling framework includes analysis of both the first and fifth liter.

Why Sampling Protocol Changes Matter

Lead release can vary depending on:

• service-line material;
• stagnation time;
• water chemistry;
• flow disturbance;
• which portion of water is sampled.

Improved sampling is intended to better identify elevated lead conditions.

LCRI Service Line Replacement

The LCRI establishes a stronger national lead service-line replacement framework.

In general, systems will be required to replace lead and galvanized-requiring-replacement service lines under their control within 10 years, subject to specified exceptions and regulatory provisions.

Galvanized Requiring Replacement

A galvanized service line can be classified as galvanized requiring replacement, or GRR, when it meets regulatory criteria associated with current or previous downstream lead service-line conditions.

Operators should not assume that every galvanized line is automatically treated the same under the rule.

Partial Lead Service Line Replacement

The LCRI generally discourages or prohibits routine partial replacement because leaving part of a lead service line in service can continue the exposure risk.

Limited exceptions can apply for emergency repairs or specified infrastructure work.

Disturbance of Lead Service Lines

Construction, meter work, valve operation, service-line work, or other disturbances can temporarily increase lead release.

Operators should follow required customer notification and risk-mitigation procedures when disturbing known or potential lead-containing lines.

Lead Is Not Controlled by Flushing Alone

Flushing can temporarily reduce lead concentration at a tap, but it does not remove the underlying source of lead.

Long-term exposure reduction depends on:

• effective corrosion control;
• removal of lead-containing materials;
• proper monitoring;
• public communication.

Example: 90th Percentile Above 15 ppb

During the current pre-LCRI transition period, suppose a system has a 90th-percentile lead result above 15 ppb.

This is a lead action-level exceedance.

The system must follow the applicable LCR requirements, including required public notification and other regulatory actions.

Example: One High Sample

A single lead sample above 15 ppb does not automatically mean the system's 90th percentile exceeds the action level.

However, the individual result can still require customer notification or other action under applicable rules.

Example: Low 90th Percentile

A system has a lead 90th percentile below the action level.

This does not mean corrosion control can be ignored.

The system must continue required monitoring and maintain treatment conditions.

Example: Treatment Change

A plant changes source water and substantially changes alkalinity and chloride-to-sulfate conditions.

Even if finished water meets ordinary source-water quality targets, the change can alter corrosion behavior.

The operator should evaluate corrosion-control consequences before and after the change.

Example: Orthophosphate Feed Failure

A system relies on orthophosphate for corrosion control.

The feed pump fails for an extended period.

Even if no immediate customer complaint occurs, corrosion-control performance can be compromised.

The operator should respond according to the system's approved treatment and regulatory procedures.

Action Level Versus MCL

A common exam mistake is calling the lead action level an MCL.

The LCR uses action levels as treatment-technique triggers.

For exam purposes:

• lead action level is not a traditional MCL;
• copper action level is not a traditional MCL;
• exceeding an action level triggers required regulatory actions.

Common Lead and Copper Rule Mistakes

• Calling the lead action level an MCL.
• Averaging tap samples instead of using the required 90th-percentile method.
• Assuming one high sample automatically equals a system-wide action-level exceedance.
• Ignoring corrosion-control treatment after tap results improve.
• Assuming finished-water plant samples replace compliance tap samples.
• Ignoring service-line material inventories.
• Confusing the current 15 ppb lead action level with the future 10 ppb LCRI action level.
• Assuming all LCRI requirements are already in effect before November 1, 2027.
• Failing to evaluate corrosion risk when source water or treatment changes.
• Assuming flushing permanently solves lead exposure.

A Practical Operator Review

1. Know the system's current lead and copper monitoring schedule.
2. Verify approved compliance sampling locations.
3. Review sampling instructions before each monitoring period.
4. Calculate or verify the regulatory 90th-percentile result.
5. Compare results with the applicable current action levels.
6. Maintain corrosion-control treatment and water-quality parameters.
7. Review service-line inventory information.
8. Investigate changes in source water or treatment that could affect corrosion.
9. Complete required customer notification, public education, and reporting.
10. Track the transition to LCRI requirements effective beginning November 1, 2027.

What to Remember for the Exam

• Lead and copper commonly enter drinking water through corrosion of plumbing materials.
• The Lead and Copper Rule is primarily a treatment-technique regulation.
• Compliance monitoring is conducted at selected customer taps.
• The traditional lead action level during the current transition period is 15 ppb.
• The copper action level is 1.3 mg/L.
• Action levels are not traditional MCLs.
• Lead and copper compliance is evaluated using the regulatory 90th-percentile calculation.
• Corrosion control treatment reduces release of lead and copper from plumbing materials.
• Important corrosion-control variables include pH, alkalinity and corrosion inhibitor treatment.
• Systems must maintain required water-quality parameters when corrosion control is used.
• Initial service-line inventories were required by October 16, 2024.
• Known and potential lead-containing service lines require customer communication under applicable rules.
• Selected LCRR requirements have been in effect since October 16, 2024.
• Most LCRI requirements begin November 1, 2027.
• The LCRI lowers the future lead action level to 10 ppb.
• The LCRI retains the copper action level at 1.3 mg/L.
• The LCRI strengthens lead service-line replacement and tap-sampling requirements.
• A single high lead result is not automatically the same as a 90th-percentile action-level exceedance.
• Changing source water or treatment can change corrosion behavior.
• Effective corrosion control, monitoring, service-line replacement, and public communication work together to reduce lead exposure.