EPA Maximum Contaminant Levels (MCLs) for PFAS

An overview of the National Primary Drinking Water Regulation for Per- and Polyfluoroalkyl Substances (PFAS) and a description of the actions MassDEP will be taking

On April 10, 2024, EPA announced the final National Primary Drinking Water Regulation establishing MCLs for six PFAS.  EPA established individual MCLs for these six PFAS: PFOA, PFOS, PFHxS, PFNA, and GenX (HFPO-DA).  In addition, EPA established a Hazard Index MCL for mixtures of four PFAS to account for the combined levels of these PFAS in drinking water.

Table of Contents

EPA National Primary Drinking Water Regulation

EPA established these Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) for PFAS in drinking water.


Information about the national PFAS MCLs is available on the EPA webpage.

Establishment of MCLs requires EPA to take into consideration costs, benefits, feasibility, and public comments. MassDEP looks forward to engaging with EPA and to communicating with the public and with public water systems to help them understand what actions are being taken. 

The establishment of an MCL for likely carcinogens (PFOS and PFOA) requires that EPA set the level as close as feasible to the health-based Maximum Contaminant Level Goal of zero for PFOS and PFOA. 

MassDEP Plan for PFAS regulations

States are required to establish regulations that are no less stringent than the federal standards within two years of the promulgation of the federal MCL, with the possibility of an extension of up to two years.  The current Massachusetts regulations, which established a PFAS6 MCL of 20 parts per trillion (ppt), are less stringent than the new federal MCLs and will be revised. In addition, the federal MCLs cover two additional PFAS (PFBS and GenX) that are not included in the current Massachusetts PFAS6 MCL and will need to be regulated. MassDEP will be proposing amendments to its PFAS regulations to be at least as stringent as the EPA MCLs and will be holding public hearings to receive public input on this proposal. 

The EPA MCLs are applicable to Community (COM) and Non-Transient Non-Community (NTNC) Public Water Systems (PWS) only and not toTransient Non-Community (TNC) PWS.  A PWS is a system for the provision to the public of water for human consumption, through pipes or other constructed conveyances, if such system has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days of the year.  A COM water system serves at least 25 year-round residents. An NTNC water system serves at least 25 of the same persons approximately four or more hours per day, four or more days per week, more than 180 days per year, such as a school or workplace. A TNC water system serves water to 25 different persons at least 60 days of the year. Some examples of these types of systems are restaurants, motels, campgrounds, parks, golf courses, ski areas, and community centers. 

The EPA MCLs are not applicable to TNC water systems. However, the current Massachusetts PFAS regulation required baseline sampling for all TNCs and health assessments by the MassDEP Office of Research and Standards, as needed. MassDEP will reevaluate and contact TNCs that previously received ORS determinations, as well as any other TNCs identified by ORS for evaluation based on the EPA MCLs.

MassDEP is already working with the PWS that exceeded the Massachusetts PFAS6 MCL to address PFAS in their water source and will be working with the additional PWS that exceed the EPA MCLs.  Those with PFAS6 concentrations exceeding the current Massachusetts MCL must provide Public Notice and develop and implement a plan to remediate or replace the water supply.

MassDEP is offering grants and zero percent interest loans to assist water systems to address PFAS.


Briefing for Public Water Suppliers

On May 28, 2024, MassDEP held a briefing for PWS covering:

  • EPA’s timeline and the Massachusetts' timeline for implementing the federal regulations
  • MassDEP’s timeline for evaluating the science, holding public hearings and issuing state regulations.
  • How EPA’s MCLs differ from the Massachusetts PFAS6 MCL
  • The impact of the EPA MCLs on Massachusetts’ PWS and what PWS should be doing now to prepare for these regulations.

A video recording of the briefing, and a copy of the slides, and a copy of the Q&As from the presentation and are located below.

Additional Resources

Date published: April 12, 2023

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