For most contaminants, EPA sets an enforceable regulation called a maximum contaminant level (MCL). However, because lead and copper contamination of drinking water often results from corrosion of the plumbing materials belonging to water system customers, EPA established a treatment technique rather than an MCL for lead and copper.

The lead and copper treatment technique regulation requires water systems to control the corrosiveness of their water. The Lead and Copper Rule defines the acceptable limits (action levels) for lead and copper in drinking water. 90 percent of a water system's service households must be below the following limits for lead and copper:

• The action level for copper is 1.3 ppm (milligrams per liter, mg/l).
• The action level for lead is 15 ppb (micrograms per liter, µg/l).

If more than 10% of tap water samples exceed the action level, water systems must take additional steps.

Community (water districts, mobile home parks, apartment buildings) and non-transient, non-community (schools, businesses) public water systems must test for lead and copper. Water systems that pass two consecutive six month rounds can go to an annual sampling schedule (Reduced Monitoring). The minimum number of samples they need to collect are also reduced (unless they are already collecting the minimum of 5). Reduced monitoring samples must be collected in a summer month (June, July, August, or September). After the water system passes three annual rounds of lead and copper sampling, they can request to sample once every three years.

Water systems are responsible for the quality of their water to the customers' tap. Lead and copper samples must be a first draw tap sample or a lead service line sample, and are collected at the customers' homes, not at the water system's source. The Lead and Copper Rule requires the water system to select homes from high risk groups first. High risk structures include buildings with lead service lines, lead solder, or structures built between 1982 and 1987. The list of sites must be submitted to the Drinking Water Program and changes in the testing schedule must be documented. Information on choosing sampling site locations can be found in the Sample Site Selection guide for Community Water Systems and the Sample Site Selection Guide for Non-Community Water Systems.

All community water systems are required to include a short informational statement in their Consumer Confidence Report regarding lead in drinking water. The mandatory language is available can be found on the Lead and Copper public education and notification page.

The Lead and Copper Rule [40 CFR §141.85(d)] requires all public water systems to provide the results of the lead sample taken to each consumer that collected a sample at the specific sample site from which the sample was taken. Consumer notification is required for each round of lead and copper tap monitoring.

Non-transient, non-community systems such as schools and businesses can post the results in a conspicuous location provided all consumers have access to the information.

Each public water system sampling for lead and copper must complete the Lead and Copper Consumer Notification Form (PDF) and provide a copy to each consumer as described above. In addition, each public water system must submit the Certification for Consumer Notification (PDF) to the Drinking Water Program within 30 days after the public water system is notified of the lead sampling results.

When test results for lead show that ninety percent of the samples are not at or below the EPA's action level of 15 ppb (parts per billion), a water system must conduct a Public Education Program within 60 days. All community water systems are also required to include a short informational statement in their Consumer Confidence Report regarding the lead exceedance.