On March 14, 2023, the U.S. Environmental Protection Agency published its long-awaited Maximum Contaminant Levels (MCLs) for PFOS and PFOA in drinking water. The MCL for both constituents individually is four parts per trillion (ppt), which is lower than many state clean-up standards or state-level MCLs. Additionally, EPA set health-based Maximum Contaminant Level Goals (MCLGs) for PFOA and PFOS at zero. EPA also proposed a Hazard Index approach of 1.0 for four additional PFAS and their mixtures: PFHxS, HFPO-DA and its ammonium salt (aka GenX chemicals), PFNA and PFBS.

Public water systems, such as municipal water companies, are ultimately responsible for MCL compliance, but industries that discharge into public water systems need to prepare for an influx of inquiries and test requirements related to PFAS as the water systems strive to meet these new standards. Upstream efforts will be particularly aggressive within systems that do not (and cannot) currently meet the MCLs.

If you would like to learn more about the PFAS testing in your geography to date, EPA’s PFAS Analytic Tools through ECHO (Enforcement and Compliance History Online) is a great place to start. The Tools, while not comprehensive, summarize environmental sampling data, drinking water supply data, sites potentially impacted by PFAS and PFAS handler data, all of which are useful when assessing regulatory risk.

These MCLs will generate a tremendous number of comments from the regulated community and other stakeholders, and they will likely have a phase in period before they become effective. But the MCLs confirm EPA’s commitment to regulating PFAS and provide a draft target upon which water systems will base upstream inquiries and testing. Now is the time to assess your company’s regulatory risk and make plans for proactive risk mitigation and compliance.