The Lead and Copper Rule (LCR) reduces risks to drinking water consumers from lead and copper that can enter drinking water as a result of corrosion of plumbing materials. The LCR requires water systems to sample at taps in homes with leaded plumbing materials. Depending upon the sampling results, water systems must take actions to reduce exposure to lead and copper, including corrosion control treatment, public education, and lead service line replacement. The LCR was promulgated in 1991 and, overall, has been effective in reducing the levels of lead and copper in drinking water systems across the country. However, lead crises in Washington, DC, and in Flint, Michigan, and the subsequent national attention focused on lead in drinking water in other communities, have underscored significant challenges in the implementation of the current rule, including a rule structure that, for many systems, only compels protective actions after public health threats have been identified. Key challenges include the rule's complexity; the degree of flexibility and discretion it affords systems and primacy States with regard to optimization of corrosion control treatment; compliance sampling practices, which in some cases, may not adequately protect from lead exposure; and limited specific focus on key areas of concern such as schools. There is a compelling need to modernize and strengthen implementation of the rule--to strengthen its public health protections and to clarify its implementation requirements to make it more effective and more readily enforceable.