EPA Announces Final PFAS National Primary Drinking Water Regulation

After several years of per- and polyfluoroalkyl substances (PFAS) making news headlines, the United States Environmental Protection Agency (EPA) announced on April 10, 2024, its highly anticipated final National Primary Drinking Water Regulation (NPDWR) for PFAS. This final rule establishes Maximum Contaminant Levels (MCLs) for five compounds in drinking water (PFOA, PFOS, PFHxS, PFNA, and HFPO-DA) individually and uses a Hazard Index for PFAS mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA, and PFBS to account for the combined (or additive) potential for toxic effects. Tuesday’s announcement comes more than a year after the proposed rule was announced on March 14, 2023.

The Federal Maximum Contaminant Levels

The final rule establishes Maximum Contaminant Levels (MCLs) for six PFAS in drinking water and a Hazard Index MCL, determined by dividing the concentration of each of the four analytes (PFHxS, PFNA, HFPO-DA, and PFBS) by the calculated health-based water concentrations for each compound individually. The summed value of the quotients is the hazard index. The following table summarizes the final MCLs.


Rob Little Practice Leader Drinking Water

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What This Means for Water Suppliers

The EPA is providing three years for water systems to complete initial monitoring for PFAS, which will be followed by ongoing compliance monitoring. Beginning in 2027, water systems must provide the public with information on the PFAS concentrations in their drinking water. Public water systems that find PFAS concentrations that exceed one or more of these MCLs must take action by 2029 to reduce the concentrations in drinking water to levels below the MCLs. The public must also be notified of any MCL violations.

We are Ready to Help

Woodard & Curran’s engineers and scientists have partnered with clients across the country to address the presence of PFAS in both drinking water and the environment. We have worked with communities and water agencies for years in anticipation of these federal regulatory measures. In many cases this work has been driven by states that set their own limits for PFAS in the absence of an enforceable federal standard.

In Hudson, Massachusetts, our drinking water experts implemented a treatment system to work in conjunction with the existing water treatment plant. Similarly, we partnered with the water department in Mansfield, Massachusetts, to pilot test and implement PFAS treatment systems at two existing sources. Our experts have also helped to develop innovative treatment techniques to remediate PFAS chemicals where they are found in groundwater aquifers, and have conducted studies to determine the background  PFAS concentrations found in soil as a result of aerial transport and precipitation. Our environmental services team is also working to better understand how PFAS interacts with the water cycle and navigating an evolving regulatory landscape with our clients to address PFAS in soil and groundwater.

Regardless of where PFAS is found, we understand the potential ramifications that arise with new regulatory measures such as the EPA’s final PFAS National Primary Drinking Water Regulation. Our experts are positioned to not only assist in mitigation projects, but also support public agencies’ pursuit of fiscal planning to protect public health.


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