EPA Publishes Proposed National Primary Drinking Water Standards for Select PFAS Compounds

On March 14, 2023, the United States Environmental Protection Agency (US EPA) published a much-awaited proposed National Primary Drinking Water Regulation (NPDWR) for six per- and polyfluoroalkyl substances (PFAS). The move sets the stage for legally enforceable Maximum Contaminant Levels (MCLs) and non-enforceable Maximum Contaminant Level Goals (MCLGs) for the following six PFAS compounds: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO, commonly known as GenX), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS). PFAS are a group of synthetic chemicals that are widely distributed and persistent in the environment.

The proposed MCLs and MCLGs are detailed in the table below. The US EPA has proposed concentration-based MCLs (4 parts per trillion, or PPT) for PFOA and PFOS. The proposed MCL for PFNA, PFHxS, PFBS, and HFPO is based on the calculated Hazard Index (HI) for the combined mixture of these four compounds. Several of the individual Health Based Water Concentrations (HBWCs) used by US EPA to derive the HI are also in the low ppt level (e.g., 10 ppt for PFNA and GenX, and 9 ppt for PFHxS).

According to the Interstate Technology Regulatory Council (ITRC), thirty states and ten non-US countries currently regulate PFAS concentrations in drinking water and/or groundwater. The proposed MCLs are lower than current drinking water standards established by all US states except Illinois. The proposed values are also lower than the drinking water standards in most other countries.

The US EPA has stated that it anticipates finalizing the regulation by the end of 2023. A public comment period will open once the proposed rule is published in the Federal Register. Additional information regarding the proposed NPDWR for PFAS, including a schedule for two informational webinars and a public hearing, is available on US EPA’s website here: Per- and Polyfluoroalkyl Substances (PFAS) | US EPA.

Verdantas provides PFAS consulting services to our clients and has been tracking regulatory and technical developments related to PFAS for many years. We understand the wide-ranging implications of these proposed criteria for our clients. Beyond implications for drinking water, the proposed MCLs and MCLGs are expected to affect state and federal cleanup criteria for environmental remediation. If you are a public or private water system or have questions about state- or federally-regulated site assessment and remediation projects, we can help. Reach out to your local Verdantas office or contact us to be connected directly with one of our PFAS experts.