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Water: The Six-Year Review

Six-Year Review of Drinking Water Standards

The Safe Drinking Water Act (SDWA) requires EPA to review each National Primary Drinking Water Regulation (NPDWR) at least once every six years and revise them, if appropriate. The purpose of the review, called the Six-Year Review, is to identify those NPDWRs for which current health effects assessments, changes in technology, and/or other factors provide a health or technical basis to support a regulatory revision that will maintain or strengthen public health protection.

Statutory Requirements for the Six-Year Review

Section 1412(b)(9) of the Safe Drinking Water Act states,

"The Administrator shall, not less often than every 6 years, review and revise, as appropriate, each national primary drinking water regulation promulgated under this title. Any revision of a national primary drinking water regulation shall be promulgated in accordance with this section, except that each revision shall maintain, or provide for greater, protection of the health of persons."

Overview of the Six-Year Review Efforts

Since the 1996 SDWA Amendments were enacted, the Agency has completed two comprehensive reviews of existing National Primary Drinking Water Regulations.  The links below provide more information about the first and second Six-Year Reviews.

Review of the Fluoride Drinking Water  Regulation

On January 7, 2011, the Agency announced its intent to review the national  primary and secondary drinking water regulations for fluoride. By initiating the current review, EPA is  following up on a commitment made in the second Six Year Review (SY2), which  was released in March 2010. In SY2, the  Agency indicated that the Office of Water was in the process of updating its health and exposure assessments and that when the Agency finalized these assessments, it would review the existing drinking water regulation to determine whether revisions are appropriate.

The Agency released the new risk and exposure assessments on January 7, 2011. These assessments address recommendations made by the  National Research Council (NRC) of the National Academies of Science  (NAS).The NRC review was conducted at  the request of the EPA in 2003 as part of the first Six Year Review, in  which EPA found that new health and exposure data were available on orally  ingested fluoride. In 2006, NRC  published their evaluation in a report entitled Fluoride in Drinking Water: A Scientific Review of EPA's Standards. In this report, the NRC recommended that EPA  update its fluoride risk assessment to include new data on health risks and  better estimates of total exposure. Based  on the new assessments, EPA will begin the process of reviewing the current  drinking water standards for fluoride to decide whether revisions are appropriate.

Other information or activities related to fluoride:

Other Related Efforts

In a related effort, SDWA includes a process that we must follow to identify and list unregulated contaminants which may require a national drinking water regulation in the future. EPA must publish this list of unregulated contaminants (called the Contaminant Candidate List or CCL) and decide whether to regulate at least five or more contaminants on the list (called Regulatory Determinations). EPA uses this list of unregulated contaminants to prioritize research and data collection efforts to help us determine whether we should regulate a specific contaminant.


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