This document provides guidance to states and the US Environmental Protection Agency (EPA) exercising primary enforcement responsibility under the Safe Drinking Water Act (SDWA), concerning how EPA interprets the Public Notification (PN) Rule promulgated under the SDWA. It also provides guidance to the public and the regulated community on how EPA intends to exercise its discretion in implementing the statute and regulations. This guidance is designed to implement national policy on these issues. Throughout this document, the terms state and states are used to refer to all types of primacy agencies including states, US territories, Native American tribes, and EPA regional offices that maintain state primacy.