Lead and Copper Rule
The Lead and Copper Rule is a United States federal regulation which limits the concentration of lead and copper allowed in public drinking water at the consumer's tap, as well as limiting the permissible amount of pipe corrosion occurring due to the water itself. The U.S. Environmental Protection Agency first issued the rule in 1991 pursuant to the Safe Drinking Water Act. The EPA promulgated the regulations following studies that concluded that copper and lead have an adverse effect on individuals. The LCR sought to therefore limit the levels of these metals in water through improving water treatment centers, determining copper and lead levels for customers who use lead plumbing parts, and eliminating the water source as a source of lead and copper. If the lead and copper levels exceed the "action levels" water suppliers are required to educate their consumers on how to reduce exposure to lead. A 2004-2005 study of the LCR by the EPA noted that the system had been effective in 96 percent of systems serving at least 3,300 people.
The EPA has stated that the LCR has reduced exposure to lead "that can cause damage to brain, red blood cells, and kidneys, especially for young children and pregnant women." It also explained that the rule has reduced copper exposure "that can cause stomach and intestinal distress, liver or kidney damage, and complications of Wilson’s disease in genetically predisposed people."
Background
Although lead is a known poison, the mechanical and chemical characteristics of the metal continue to keep lead as an important component in many products. In water supply, lead's durability and workability made it preferable for use as water pipes. Lead alloys are used for plumbing fittings, and lead solders were also preferred. While state and local governments began to prohibit installation of lead pipes early in the twentieth century, lead alloys continued to be used. Alternative pipe materials have been iron, copper, and later plastics. Although new lead pipes weren't installed later in the 20th century, some existing lead pipes remain in service in many cities.The U.S. Public Health Service published a non-enforceable standard for lead in 1925, consisting of a tolerance limit of 0.1 mg/L.
Partially because of the continued use of lead pipes, some states regulated the corrosivity of water put into the distribution system. Waters which would deposit a protective coating on the pipes rather than dissolving the pipe were preferred. Corrosion indexes such as pH or Langelier Saturation Index are not necessarily representative of the lead corrosion potential in a particular water/pipe system, nor did they measure the amount of lead to which customers were exposed.
In the second half of the twentieth century, concern was growing about what constituted a safe level of lead.
The 1986 Safe Drinking Water Act amendments defined "lead-free" plumbing and prohibited the use of plumbing for public water supply that did not meet the new definition. The amendments also required the EPA to set standards limiting the concentration of lead in public water systems.
Adoption
The EPA first issued the Lead and Copper Rule on June 7, 1991. The latest modification was issued October 10, 2007.Following the adoption of the 1991 rule, public water systems serving more than 50,000 people were required to survey their own corrosion control systems and to replace their pipelines with state-approved corrosion control by January 1, 1997. Suppliers who served a smaller number of people only had to replace their pipelines if action levels were exceeded at the tap.
The EPA published the Lead and Copper Rule Minor Revisions in January 2000. This rule required water suppliers to install the best available corrosion control mechanisms and to continually observe water levels, even if corrosion control was implemented. The revisions were effective April 11, 2000.
Additional corrections and minor revisions were made in 2004 and 2006.
The EPA published a white paper in 2016 discussing options for additional revisions to the rule.
Congress passed the Reduction of Lead in Drinking Water Act in 2011. This amendment, effective in 2014, tightened the definition of "lead-free" plumbing fixtures and fittings. To implement the amendment, EPA published a proposed rule in 2017. The final rule is pending as of 2020.
EPA published another proposed rule on November 13, 2019 addressing lead issues. The proposal would mandate additional requirements for sampling tap water, corrosion control, replacement of lead service lines, public outreach and testing water in schools.
Synopsis
Most of the lead found in drinking water leaches from lead service lines, the customer's pipes, fittings, and solder rather than from the source water. As a result, sampling is done from the customer's taps.Although the chemistry is complicated, the lead dissolved in the water generally increases with the amount of time the water has been in contact with the pipe. This is why first draw samples must be water which has stood motionless for at least 6 hours.
The limit in LCR is called an Action Level. It is a limit on the 90th percentile of the samples, not a Maximum Contaminant Level that applies to all samples - it is only broken when more than 10 percent of samples exceeds the level. The action level for lead is 0.015 mg/L and the action level for copper is 1.3 mg/L.
Actions must be taken if the Action Level is hit. This may include investigation, recommendation of treatment, installation of treatment, checking of source water, removal of lead containing plumbing, and public education.
The site selection process prioritizes sites by the likelihood of finding high lead concentrations which could impact people. Building codes and building records may be used to estimate the types of plumbing and solders at various buildings. Residential buildings are preferred over commercial, for sampling. Only taps from which water is consumed are tested. The age of plumbing is taken into account, as older piping may reach an equilibrium with the water.
Unusualness
Because the source of lead and copper is generally the customer-owned piping rather than any part of the water supplier's plumbing, equipment, or even the original source of water, the Lead and Copper Rule is quite unlike any of the other provisions of the National Primary Drinking Water Regulations. To some extent, the water supplier is made responsible for the quality of water sampled at pipes and locations completely out of the supplier's control. The most unusual features of the rule follow from this difference.While MCLs are risk-based, and the code requires the water supply take various actions based on the MCL, the Lead and Copper Rule regulates the level of contamination at the customers' taps based on "action levels." No MCL is set for lead or copper. This method allows some percentage of the customer taps to exceed the "action level" without the water system having to take action. Especially for the larger systems, having the water supplier change the tendency of the water to dissolve lead in the customer plumbing may be more cost effective than having thousands of customers replace plumbing.
Also, because the source of lead and copper is the customer plumbing, lead and copper sampling is specified to be "first draw."
Most other water samples are taken by the water supplier's personnel. Trained personnel using consistent procedures generally yield more reliable data. The first draw sampling procedures make water supplier sampling impractical. Rather than have a technician spend six hours in a customer's home, the water supplier may leave the sample bottles and sampling instructions with the consumer.