On June 7, 1991, the United States Environmental Protection Agency or EPA, published in the Federal Register, a regulation to control lead and copper in drinking water. This regulation is known as the Lead and Copper Rule (also referred to as the LCR or 1991 Rule throughout this document). On January 12, 2000, EPA published minor revisions to the 1991 Rule. The purpose of the Lead and Copper Rule Minor Revisions (LCRMR) is to eliminate unnecessary requirements, streamline and reduce monitoring and reporting burdens, and promote consistent national implementation. In some cases, EPA has added language which clarifies requirements and corrects oversights in the original rule. EPA calls the revisions minor because they do not affect the lead and copper maximum contaminant level goals, action levels, or other basic regulatory requirements to monitor for lead and copper at the tap and to optimize corrosion control. This guidance document has been developed for you, the water system owner and operator of community water systems (CWSs) and non-transient, non-community water systems (NTNCWSs). It provides a comprehensive discussion of the monitoring and monitoring-related reporting requirements of the LCR, as amended by the LCRMR.