This document provides guidance to EPA Regions and states exercising primary enforcement responsibility under the Safe Drinking Water Act (SDWA) regarding implementation of the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) under the SDWA. It also provides guidance to the public and the regulated community regarding the U.S. Environmental Protection Agency's (EPA's) interpretation of the statute and regulations. This guidance is designed to implement national policy on these issues. The SDWA provisions and EPA regulations described in this document contain legally binding requirements. This document does not substitute for those requirements, nor is it a regulation itself. It does not impose legally-binding requirements on EPA, states, or the regulated community and may not apply to a particular situation based upon the circumstances. EPA and state decision makers retain the discretion to adopt approaches on a case-by-case basis that differ from this guidance, where appropriate. Any decisions regarding a particular facility will be made based on the applicable statutes and regulations. Therefore, interested parties are free to raise questions and objections about the appropriateness of the application of this guidance to a particular situation.