Per- and Polyfluoroalkyl Substances (PFAS)

Final PFAS National Primary Drinking Water Regulation

• Summary
• Supporting Materials
  • General Information
  • Communications Toolkit
  • Technical Information for States, Tribes and Water Systems
  • Español
• Regulatory Information and Supporting Documents
• Webinars
• Background

On May 14, 2025, EPA announced the agency will keep the current National Primary Drinking Water Regulations (NPDWR) for PFOA and PFOS. As part of this action, EPA also announced its intent to extend the PFOA and PFOS Maximum Contaminant Level compliance deadlines and establish a federal exemption framework. Additionally, EPA announced its intent to rescind the regulations and reconsider the regulatory determinations for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index mixture of these three PFAS plus PFBS to ensure the determinations and any resulting drinking water regulation follow the Safe Drinking Water Act process. For more information, see EPA's Press Release.

Rule Summary

On April 10, 2024, EPA announced the final NPDWR for six PFAS. To inform the final rule, EPA evaluated over 120,000 comments submitted by the public on the rule proposal, as well as considered input received during multiple consultations and stakeholder engagement activities held both prior to and following the proposed rule. EPA expects that over many years the final rule will prevent PFAS exposure in drinking water for approximately 100 million people, prevent thousands of deaths, and reduce tens of thousands of serious PFAS-attributable illnesses.

EPA is also making unprecedented funding available to help ensure that all people have clean and safe water. In addition to the final rule, EPA announced $1 billion in available funding through the Infrastructure Investment and Jobs Act to help states and territories implement PFAS testing and treatment at public water systems and to help owners of private wells address PFAS contamination.

EPA established legally enforceable levels, called Maximum Contaminant Levels (MCLs), for six PFAS in drinking water: PFOA, PFOS, PFHxS, PFNA, and HFPO-DA as contaminants with individual MCLs, and PFAS mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA, and PFBS using a Hazard Index MCL to account for the combined and co-occurring levels of these PFAS in drinking water. EPA also finalized health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these PFAS.

Compound Final MCLG Final MCL (enforceable levels)1 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

1 Compliance with MCLs is determined by running annual averages at the sampling point.

The final rule requires:

• Public water systems must monitor for these PFAS and have three years to complete initial monitoring (by 2027), followed by ongoing compliance monitoring. Water systems must also provide the public with information on the levels of these PFAS in their drinking water beginning in 2027.
• Public water systems have five years (by 2029) to implement solutions that reduce these PFAS if monitoring shows that drinking water levels exceed these MCLs.
• Beginning in five years (2029), public water systems that have PFAS in drinking water which violates one or more of these MCLs must take action to reduce levels of these PFAS in their drinking water and must provide notification to the public of the violation.

Supporting Materials

General Information

• General Fact Sheet: EPA's Final Rule to Limit PFAS in Drinking Water (pdf) (162.45 KB)
• Frequently Asked Questions and Answers: Final PFAS National Primary Drinking Water Regulation (pdf) (218.52 KB)
• Fact Sheet: Reducing PFAS in Your Drinking Water with a Home Filter (pdf) (146.92 KB)
• Presentation: Overview EPA PFAS NPDWR (pdf) (447.13 KB)
• Press Release
• Español

Information for States, Tribes, and Water Systems

• Frequently Asked Questions and Answers for Drinking Water Primacy Agencies: Final PFAS National Primary Drinking Water Regulation (pdf) (285.31 KB)
• Fact Sheet: Understanding the Final PFAS National Primary Drinking Water Regulation Hazard Index Maximum Contaminant Level (pdf) (211.86 KB)
• Fact Sheet: Benefits and Costs of Reducing PFAS in Drinking Water (pdf) (191.9 KB)
• Fact Sheet: Small and Rural Water Systems (pdf) (212.93 KB)
• Fact Sheet: PFAS NPDWR Monitoring and Reporting (pdf) (521.55 KB)
• Fact Sheet: Treatment Options for Removing PFAS in Drinking Water (pdf) (189.59 KB)
• Fact Sheet: Comparison Between EPA's Proposed and Final PFAS NPDWR (pdf) (176.83 KB)
• For additional resources to help states and water utilities implement the PFAS NPDWR, see EPA's PFAS NPDWR Implementation website.

Regulatory Information

• Federal Register Notice: Final PFAS National Primary Drinking Water Regulation
• Federal Register Notice: Final PFAS National Primary Drinking Water Regulation; Correction
• Find additional supporting materials, including all EPA Technical Support Documents informing the final rule and EPA's Response to Public Comments on the Proposed PFAS NPDWR. These documents, as well as all other supporting information for the Final PFAS NPDWR, are available at www.regulations.gov under Docket ID: EPA-HQ-OW-2022-0114.

Webinars

EPA held three informational webinars for communities, water systems, and other drinking water professionals about the final PFAS NPDWR. The three webinar webinars were similar, with each intended for specific audiences.

• April 16, 2024 General Overview Webinar on the Final PFAS NPDWR
  • General Overview Webinar Presentation: Final PFAS NPDWR (pdf) (500.09 KB)
  • Webinar Recording: General Overview of Final PFAS NPDWR
• April 23, 2024 Drinking Water Utilities and Professionals Technical Overview Webinar on the Final PFAS NPDWR
  • Drinking Water Utilities and Professionals Technical Overview Webinar on PFAS NPDWR (pdf) (773.89 KB)
  • Webinar Recording: Drinking Water Utilities and Professionals Technical Overview of Final PFAS NPDWR
• April 30, 2024 Small Drinking Water Systems Webinar Series on Final PFAS NPDWR and PFAS Drinking Water Treatment
  • Small Drinking Water Systems Webinar Presentation on Final PFAS NPDWR (pdf) (573.21 KB)

Background

Under the Safe Drinking Water Act, EPA has the authority to set enforceable National Primary Drinking Water Regulations (NPDWRs) for drinking water contaminants and require monitoring of public water systems. In March 2021, EPA published Regulatory Determinations for Contaminants on the Fourth Contaminant Candidate List which included a final determination to regulate PFOA and PFOS in drinking water. As a part of that final determination, EPA indicated it would also evaluate additional PFAS and consider regulatory actions to address groups of PFAS.

On March 24, 2023, EPA proposed the PFAS NDPWR. Concurrent with the proposed rule, EPA also announced preliminary regulatory determinations for PFHxS, PFNA, HFPO-DA, and PFBS in accordance with the Safe Drinking Water Act regulatory development process. EPA proposed to regulate PFOA and PFOS with individual MCLs and PFHxS, PFNA, HFPO-DA, and PFBS using a Hazard Index which accounts for co-occurring mixtures of these four PFAS. Concurrent with the final PFAS NPDWR announced on April 10, 2024, EPA also announced final individual regulatory determinations for PFHxS, PFNA, and HFPO-DA, and final regulatory determination for mixtures containing two or more of these three PFAS and PFBS. This regulation will also remove many other PFAS when they co-occur with these regulated PFAS.

Further Information

To learn more about PFAS and to find important background information to support understanding the details of specific actions EPA takes to address PFAS and other emerging events related to PFAS.