Pennsylvania PFAS Regulatory Changes Anticipated with EPA’s Final PFAS MCLs on the Horizon

January 18, 2024
Bryan P. Franey, Esq., Jessica D. Hunt, Esq. and Giselle F. Davidian, Esq.
MGKF Special Alert - 2024 Pennsylvania Forecast

On January 14, 2023, the Pennsylvania Department of Environmental Protection (PADEP) established drinking water standards for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).  Specifically, DEP established a Maximum Contaminant Level (MCLs) and Maximum Contaminant Level Goals (MCLGs) for PFOS at 18 parts per trillion (ppt) and 14 ppt, respectively, and 14 ppt and 8 ppt, respectively, for PFOA (collectively the Pennsylvania MCLs).  Public water systems serving more than 350 persons and bottled, vended, retail, and bulk systems are required to begin conducting initial quarterly monitoring to demonstrate compliance with the Pennsylvania MCLs beginning January 1, 2024.  Initial monitoring for public water systems serving less than 350 persons will not begin until January 1, 2025. Shortly after DEP finalized its PFAS MCLs, in March 2023, the United States Environmental Protection Agency (EPA) proposed national primary drinking water standards of 4 ppt for PFOA and PFOS, and a hazard index for a combination of perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS), and hexafluoropropylene oxide (HFPO) dimer acid and its ammonium salt (GenX) (collectively the federal MCLs). The federal MCLs, once effective, will automatically become Pennsylvania’s drinking water standards. Thus, it is possible that public water systems that installed treatment to comply with Pennsylvania’s MCLs may need to install additional treatment to meet the federal MCLs if the federal MCLs are more stringent than the Pennsylvania MCLs.  Click here for more information regarding the federal MCLs.

The federal MCLs will also impact soil and groundwater cleanup standards under Pennsylvania’s Act 2 Program. Currently, Pennsylvania has groundwater and soil medium specific concentrations for PFOA, PFOS, and PFBS, as follows:       


  • Soil: 4.4 mg/kg (residential), 64 mg/kg (nonresidential)
  • Groundwater: 14 ppt

PFOS, and

  • Soil: 4.4 mg/kg (residential), 64 mg/kg (nonresidential)
  • Groundwater: 18 ppt


  • Soil: 66 mg/kg (residential), 960 mg/kg (nonresidential)
  • Groundwater: 1,000 ppt (residential), 2,900 ppt (nonresidential)

The PFOA and PFOS MSCs are based on the Pennsylvania MCLs. Once the federal MCLs are finalized and effective, the federal MCLs will automatically become the de facto groundwater MSCs under Act 2.  Separately, DEP will need to promulgate through rulemaking new or revised residential and nonresidential MSCs for soil based on the federal MCLs.