rule continues the requirement for replacement of lead service lines (LSLs) when the action level is exceeded, but requires that a utility replace at least 3 percent of its lines annually, compared to 7 percent under the prior regulation. The EPA takes the position that although 3% is less than 7%, the new replacement program has fewer loopholes. Under the prior version, water systems were able to "test out" of the LSL replacement program, delay implementation because they did not have LSL inventories, or complete partial replacements and therefore, few water systems ever satisfied the full 7%. Several citizen and environmental groups immediately filed lawsuits challenging the rule. On March 12, 2021 EPA delayed the effective date of the rule to June 17, 2021. In December 2021 EPA announced that it is developing a proposed rule to "strengthen the regulatory framework" of the LCR. 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 (MCL) 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 (15 ppb) and the action level for copper is 1.3 mg/L. Similar to the action level is the limit in corrosion control treatment called a trigger level. It is calculated the same as an action level with a value greater than 0.010 mg/L being the trigger level for both lead and copper. Samples are gathered in systems with lead service lines and checked semi-annually if previous samples are above the action level and checked annually if the percentile exceeds the trigger level but not the action level. 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