National Primary Drinking Water Regulations; Announcement of the Results of EPA's Fourth Review of Existing Drinking Water Standards

The Safe Drinking Water Act (SDWA) requires the U.S. Environmental Protection Agency (EPA or the agency) to conduct a review every six years of existing national primary drinking water regulations (NPDWRs) and determine which, if any, are appropriate for revision. The purpose of the review, called the Six-Year Review, is to evaluate available information for regulated contaminants to determine if any new information on health effects, treatment technologies, analytical methods, occurrence, exposure, implementation, and/or other factors provides a basis to support a regulatory revision that would improve or strengthen public health protection. While EPA has recently completed several significant revisions to existing regulations and other regulatory revisions are currently underway, based on this periodic review of all NPDWRs, there are no additional candidates for regulatory revision at this time.