Lead and Copper Rule Fact Sheet

The Lead and Copper Rule was published in the Federal Register on June 7, 1991. It becomes effective on December 7, 1992. This rule requires treatment when lead and/or copper in drinking water exceeds certain levels.

Lead enters enters drinking water mainly from the corrosion of lead-containing household plumbing. Since lead and copper contamination generally occurs after water has left the public water system, the best way for the water system operator to find out if customer water is contaminated is to test water that has come from a household faucet. This type of contamination can be prevented by controlling the corrosiveness of the water supply. If corrosion control is not sufficient, lead-containing materials may have to be replaced.

Action Levels

Maximum Contaminant Level Goals (MCLG): Water systems should try to supply water which is free of lead and has no more than 1.3 milligrams of copperperliter (mg/L). This is a non-enforceable health goal.

Action Levels: When the concentration of lead or copper reaches the action level in ten percent of the total number of required samples, the water system is required to carry out the water treatment requirements of the rule. These enforceable treatment requirements are described below.

Monitoring Requirements

Lead/copper monitoring at high-risk homes.

Water systems must complete a materials evaluation of their distribution system and/or review other information to target homes that are at high risk of lead/copper (Pb/Cu) contamination. Monitoring is to be conducted at the tap in these homes, with the number of tap-sampling sites based on the population served. One sample is required at each site.

Additioanl monitoring for other water quality parameters (WQPs) affecting corrosion is required to optimize treatment and determine compliance with State lead/copper standards. Two type of systems must perform this monitoring under the following conditions.

  • large systems serving more than 50,000 persons, regardless of the lead/copper levels in tap samples.
  • Smaller systems serving less than 50,000 persons, if either action level is exceeded in tap samples.
Two types of sampling sites are specified for this purpose:
  • Within the distribution system, with the number of sites based on population served (sites may be same as for coliform sampling). Two samples are required from each site.
  • One sample at each entry point to the distribution system.

MCLG (mg/L)

Action Level (mg/L)