The Lead and Copper Rule (LCR) is a regulation applicable to all public water systems except for transient, non-community water systems under the Safe Drinking Water Act.  This rule, first promulgated in 1991 can be found in its entirety in 40 C.F.R. Part 141 and 142. After the LCR Revisions effective date, the Code of Federal Regulations is revised to include the new rule provisions.
Types of water systems
“Public water systems” are the water providers regulated under SDWA.  At its most basic, a public water system is “a system for the provision to the public of water for human consumption through pipes or other constructed conveyances, if such system has at least fifteen service connections or regularly serves at least twenty-five individuals.” There are several categories of public water systems and this is part of determining which systems are subject to the LCR Revisions.
  • Community water system (CWS) means a public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents.  A public water system may be publicly or privately owned.  City, town, subdivision, and rural water systems are examples of CWSs, but housing complexes, prisons, and nursing homes can also be CWSs. The 49,529 CWSs in the United States must comply with the LCR.
  • Non-community water system (NCWS) means a public water system that is not a community water system.
  • Transient non-community water system (TNCWS) means a public water system that is not a community water system and that does not regularly serve at least 25 of the same persons over six months per year. Examples of a TNCWSs include highway rest areas, gas stations, and campgrounds which has their own water source. The 77,129 TNCWSs in the United States are not required to meet LCR requirements.​
  • Non-transient non-community water system (NTNCWS) means a public water system that is not a community water system and that regularly serves at least 25 of the same persons over 6 months per year. Some examples are schools, child care facilities, factories, or office buildings which have their own wells or water sources to provide water inside the buildings. The 17,418 NTNCWSs in the United States must meet applicable LCR requirements.
  • Private water system or private well means any system that is not a public water system. These are not regulated by the Safe Drinking Water Act and are not required to comply with the LCR even though they may have lead pipes and lead service lines.
Classifications of Community Water Systems in the LCR
Some LCR requirements are based on the number of people a CWS serves. The three types are: 
  • Small systems serving 10,000 persons or less. There are almost 46,000 small CWSs.
  • Medium-sized systems serving 10,001 – 50,000 persons. There are more than 3,000 medium-sized CWSs.
  • Large systems serving greater than 50,000 persons.  There are fewer than 1,000 large CWSs.
Persons served
The LCR uses this term in several ways.  First, the requirements vary based on the number of people served by the system. Second, various notices that a service line is or may be lead must be given to persons served by the line. Third, persons served by water from a tap must be informed of the testing results on that tap. 
School
​According to the rule, school means any building(s) associated with public, private, or charter institutions that primarily provides teaching and learning for elementary or secondary students.

​The rule focuses on facilities built before 2014 dedicated to elementary schools, that is education for kindergarten through 8th grade.  There is mention also of high schools, e.g., educational facilities for 9th through 12th grade.
Child care facilities
​According to the rule, child care facility means a location that houses a licensed provider of child care, day care or early learning services to children, as determined by the State, local, or tribal licensing agency. The LCR revisions focus on child care facilities built prior to 2014. Individual states and communities have different standards for licensing child care facilities so the specific characteristics of these facilities will vary from locale to locale.
Service lines and connectors
​The service line is the piping that lies between the water main and the interior plumbing of a building. It may consist of one or many lengths of pipe until water reaches the structure being served. Importantly, the service line and any connector may be made of any of several materials (lead, galvanized iron or steel, copper, plastic, etc.).
 
In the LCR revisions, all of the requirements associated with replacement apply to service lines made of lead or galvanized service lines where lead pipe is, was, or may have been upstream of the galvanized pipe.  
Lead service line
​According to the rule, a lead service line (LSL) means a portion of pipe that is made of lead, which connects the water main to the building inlet. An LSL may be owned by the water system, owned by the property owner, or both. For the purposes of the LCR, a galvanized service line is considered an LSL if it ever was or is currently downstream of any LSL or service line of unknown material. If the only lead piping serving the home is a lead gooseneck, pigtail, or connector, and it is not a galvanized service line that is considered an LSL, the service line is not considered an LSL. It should be noted, however, that under Safe Drinking Water Act section 1459B, under which EPA funds LSL replacements in certain cases, a “lead service line” includes everything from the water main to the building inlet, and partial service line replacements are explicitly not allowed to be funded. 
Lead gooseneck, pigtail or connector
​According to the rule a gooseneck, pigtail or connector is a short section of piping, typically not exceeding two feet, which can be bent and used for connections between rigid service piping and/or water mains. Lead goosenecks, pigtails and connectors are not considered to be part of the LSL under the rule, but there are specific rule requirements that do apply to these connectors. It should be noted that under Safe Drinking Water Act section 1459B, under which EPA funds LSL replacements in certain cases, a “lead service line” includes everything from the water main to the building inlet, and partial service line replacements are explicitly not allowed to be funded. 
Classifications of service lines in an LSL inventory
​Because service lines have been installed and repaired over many years of service, it is possible that a service line may be made entirely of lead pipe or a combination of materials. 
  • Lead: where a portion of the service line is made of lead (excluding lead connectors, such as goosenecks, as explained above). This includes pipe with an interior lining of lead.
  • Galvanized Requiring Replacement: where a portion of the service line is galvanized iron or steel and is, was, or may have been downstream of an LSL. If the system can determine that the galvanized pipe was never downstream of an LSL then replacement is not required.
  • Non-lead: where the line is determined not to be “Lead” or “Galvanized Requiring Replacement”. If the only lead pipe it contains is a lead connector, gooseneck or pigtail, it is considered “non-lead.”
  • Lead Status Unknown: the description for service lines which the system must use until it knows if the pipe is one of the previous categories. The rule references SDWA Section 1417 which includes both the ban on installation of lead pipe and the definition of “lead-free” for newly installed materials (see 42 U.S.C. § 300g-6). The definition of lead-free has changed over time.
Full LSL replacement
According to the rule, full LSL replacement means the replacement of a lead service line (as well as galvanized service lines requiring replacement) that results in the entire length of the service line, regardless of service line ownership, meeting the Safe Drinking Water Act (SDWA) Section 1417 definition of lead free applicable at the time of the replacement. Galvanized service lines that are or were downstream of an LSL must also be replaced for a service line to be a full LSL replacement.
 
An LSL that is disconnected and left in place in the ground and remains out-of-service may be considered a full LSL replacement when a new non-lead service line is installed for use instead of the out-of-service LSL.
Partial LSL replacement
​A partial LSL replacement means replacing a portion of an LSL, leaving another segment of a service line requiring replacement in place.  Importantly, when a water system or property owner fully replaces a remaining portion of lead service line, it is a full and not a partial LSL replacement.  For the purposes of the LSL inventory, a service line that has had a partial replacement is still considered an LSL.
Situations requiring full LSL replacement
There are three situations that require full LSL replacement. The first two are based on the levels of lead in water that, when reached, trigger the LCR requirement for full LSL replacement. Once replacement is initiated after exceeding the action or trigger levels, water systems will be engaged in mandatory lead service line replacement for at least two years at the required rate.
  • Action level, when more than 10 percent of sampling sites required by the rule have levels greater than 15 microgram per liter (15 parts per billion), then systems regardless of size must immediately begin replacing lead service lines at a rate of at least 3 percent per year.
  • Trigger level when more than 10 percent of sampling sites required by the rule have levels greater than 10 microgram per liter (10 parts per billion), then systems serving more than 10,000 persons must immediately begin replacing lead service lines at a rate approved by the state.
  • Customer-initiated replacement: Water systems must facilitate achieving a full LSL replacement when a customer plans to or has recently replaced the customer’s portion of an LSL. According to the rule, when a water system is notified by the customer that the customer’s portion of the LSL will be replaced, the water system must make a good faith effort to coordinate replacement of its portion of the service line at the same time. If simultaneous replacement cannot be done, the water system must replace its portion as soon as practicable but no later than 45 days from the date the customer replaces its portion of the LSL. When a water system is notified or otherwise learns that replacement of a customer-owned LSL has occurred within the previous six months and left in place a system-owned portion of the LSL, the water system must replace its portion within 45 days of becoming aware of the customer replacement.
LSL replacement plan
​By January 2024, water systems are required to develop plans to ensure compliance with the LSL replacement requirements. These plans must include methods to identify lines for removal, replacement procedures, customer communication strategies, a rate of replacement per year, and funding sources which should also consider ways to accommodate customers unable to pay for removal of lines which they own.  These removal plans will be activated if a utility exceeds the trigger or action level.