On April 10, 2024, EPA announced the final National Primary Drinking Water Regulation (NPDWR) establishing legally enforceable Maximum Contaminant Levels (MCLs) and health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for six PFAS in drinking water. MCLs and MCLGs have been set for five individual PFAS and certain PFAS mixtures:
| Compound | Final MCLG | Final MCL (enforceable levels) |
| PFOA | Zero | 4.0 parts per trillion (ppt) (also expressed as ng/L) |
| PFOS | Zero | 4.0 ppt |
| PFHxS | 10 ppt | 10 ppt |
| PFNA | 10 ppt | 10 ppt |
| HFPO-DA (commonly known as GenX Chemicals) | 10 ppt | 10 ppt |
| Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS | 1 (unitless) Hazard Index | 1 (unitless) Hazard Index |
Public water systems have until 2029 to meet these MCLs, or will be required to provide public notification of the violations and to take other actions to reduce PFAS exceeding the MCLs in their drinking water. The Biden-Harris Administration’s announcement can be found here, and more information can be found on EPA’s website here.
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