From the Introduction: "Detections of unregulated contaminants (e.g., per- and polyfluoroalkyl substances [PFAS] and 1,4-dioxane) in public water supplies have raised questions about the quality of drinking water and increased congressional interest in the Environmental Protection Agency's (EPA's) efforts to regulate contaminants under the Safe Drinking Water Act (SDWA). Congress enacted SDWA in 1974 to address the quality of public drinking water supplies and protect public health. A key part of the act is the authority for EPA to regulate contaminants in public water supplies. [...] This report discusses the SDWA provisions relevant to how EPA evaluates contaminants to determine whether a contaminant warrants a 'national primary drinking water regulation' (NPDWR), provides an overview of the regulatory development process, and analyzes certain issues that may affect implementation of this section. In addition to the agency's work related to contaminant regulation, EPA has issued other SDWA regulations applicable to public water systems. These include regulations to reduce lead content in drinking water pipes and plumbing and to increase consumer information and public notification about drinking water quality and compliance. The report is primarily limited to EPA's implementation of the process outlined in SDWA Section 1412 'National Drinking Water Regulations' for evaluating contaminants for regulation."
CRS Report for Congress, R46652
Congressional Research Service: https://crsreports.congress.gov/