Frequent Questions

What is the "Six-Year Review?"

The Safe Drinking Water Act requires EPA to conduct a periodic review of existing National Primary Drinking Water Regulations (NPDWRs). By statute, this review must be conducted at least every six years and is, therefore, referred to as the "six-year review." On April 17th, 2002, EPA published in the Federal Register and requested comment on its six-year review of 69 NPDWRs that were established prior to 1997, including 68 chemical NPDWRs and the Total Coliform Rule (67 FR 19030). The intended purpose of the review is to identify those NPDWRs for which current health risk assessments, changes in technology, and/or other factors provide a health or technical basis to support a regulatory revision that will improve or strengthen public health protection. In March 2010, the Agency announced the review results for the Agency’s second Six-Year Review (called Six-Year Review 2).  After performing a detailed review of 71 National Primary Drinking Water Regulations (NPDWRs), the Agency believes that 67 NPDWRs remain appropriate (i.e., do not need to be revised) and four NPDWRs are candidates for regulatory revision.  These four NPDWRs include acrylamide, epichlorohydrin, tetrachloroethylene, and trichloroethylene.  In addition to the 71 NPDWRs reviewed in detail for the Six-Year Review 2, 14 other NPDWRs were included in the review but did not need a detailed review because of recent or ongoing regulatory actions (i.e., DBPs, lead and copper, and microbials).

Additional information on the six-year review, is available at

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