EPA Proposed Maximum Contaminant Level (MCL) for PFAS

An overview of the proposed EPA Maximum Contaminant Level (MCL) for PFAS and description of the actions MassDEP is taking to inform Public Water Suppliers and the public about this new standard.

On March 14, 2023 EPA released proposed National Primary Drinking Water regulations for PFOA, PFOS and four other PFAS. EPA is proposing to set a Maximum Contaminant Level (MCL) of 4.0 parts per trillion (ppt) for PFOA and 4.0 ppt for PFOS and is proposing to address four additional PFAS (GenX, PFBS, PFNA, and PFHxS) as a mixture using a Hazard Index. A Hazard Index accounts for the increased risk from mixtures of PFAS.


Table of Contents

EPA Proposed National Primary Drinking Water Regulation

EPA is proposing Maximum Contaminant Level Goals (MCLGs) for each of the six PFAS. A breakdown of the MCLs and MCLGs is shown in the table below. 

Table of Proposed MCLG and MCL Values for PFOA, PFOS, PFNA, PFHxS, PFBS, and HFPO-DA (GenX)


MassDEP applauds EPA for releasing its proposed drinking water regulations for a combination of six PFAS compounds, and will evaluate the impacts of these new draft values as EPA works toward a final rule. Massachusetts will adopt PFAS drinking water regulations that are at least as stringent as the federal standards. This will follow the release of EPA’s final drinking water standards for PFAS, will include consideration of the findings of MassDEP’s three-year review of the existing state PFAS regulations, and will be finalized before the federal deadline.

Information about the proposed PFAS MCLs is available on the EPA webpage

EPA will also be holding a public hearing on May 4, 2023, where members of the public can provide verbal comments to EPA on the rule proposal: 

MassDEP Presentation for PWS on the Proposed EPA MCLs

EPA Health Advisories for PFAS

On June 15, 2022, EPA released four drinking water health advisories for PFAS contaminants. These health advisories are:

  • Interim updated Health Advisory for PFOA = 0.004 nanograms per liter (ng/L), or parts per trillion (ppt)
  • Interim updated Health Advisory for PFOS = 0.02 ng/L
  • Final Health Advisory for GenX chemicals = 10 ng/L
  • Final Health Advisory for PFBS = 2,000 ng/L

Drinking water health advisories provide information on contaminants that can cause human health effects and are known or anticipated to occur in drinking water. EPA's health advisories are non-enforceable and non-regulatory and provide technical information to states agencies and other public health officials on health effects, analytical methods, and treatment technologies associated with drinking water contamination. EPA’s lifetime health advisories identify levels to protect all people, including sensitive populations and life stages, from adverse health effects resulting from exposure throughout their lives to these PFAS in drinking water.

For more information about EPA Health Advisories for PFAS see Drinking Water Health Advisories for PFAS Fact Sheet for Communities and Questions and Answers: Drinking Water Health Advisories for PFOA, PFOS, GenX, PFBS FAQs.

MassDEP Comment Letter on the Proposed EPA MCLs

Date published: April 12, 2023

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