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EPA proposes MCLs for six PFAS in drinking water

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The U.S. EPA announced that it is proposing enforceable Maximum Contaminant Levels (MCLs) and non-enforceable Maximum Contaminant Level Goals (MCLGs) for six per- and polyfluoroalkyl substances (PFAS).

"EPA is proposing the first-ever national standard to protect communities from PFAS in drinking water," said EPA Administrator Michael Regan during the announcement. The proposal would establish National Primary Drinking Water Regulation (NPDWR) for the following PFAS compounds: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), and hexafluoropropylene oxide dimer acid (HFPO-DA, also known as GenX Chemicals). The MCLs for PFOA and PFOS are very small, measuring only 4 parts per trillion (ppt). The ability to comply with such stringent levels can be challenging, from analysis to treatment. Thankfully, processes to measure and treat many PFAS to the ppt scale are already in operation today. The MCL for the other four PFAS compounds would use the Hazard Index approach, requiring contaminants to be below 1.0 on the Hazard Index. Under this approach, any combined concentration of the four compounds greater than 1.0 on the Hazard Index would exceed the MCL. EPA has stated that it plans to provide water systems with a web-based form that would automatically calculate the Hazard Index for the four substances' combined concentrations in drinking water. "When finalized, this proposed regulation will require public water systems to monitor these chemicals. It will also require systems to notify the public and reduce levels of these PFAS as prescribes," said Regan. The proposal is dense and deeply intricate. During the announcement, EPA provided 12 PDF documents describing different aspects of the proposal for each PFAS compound. In total, the documents provide over 4,013 pages of information.

The announcement has already prompted statements from prominent organizations across the water sector. Generally, these organizations expressed support for PFAS regulation – but also expressed concern for the significant costs that would fall onto public water systems and their ratepayers.

Water Quality Products – WQP