April 17, 2024

EPA Finalizes PFAS Drinking Water Regulation

Holland & Knight Alerts
Dianne R. Phillips | Jose A. Almanzar | Meaghan A. Colligan | Robert P. Frank | Molly Broughton


  • The long-awaited National Primary Drinking Water Regulation setting Maximum Contaminant Levels (MCLs) and MCL Goals for six per- and polyfluoroalkyl substances (PFAS) compounds in drinking water under the Safe Drinking Water Act was finalized by the U.S. Environmental Protection Agency (EPA) on April 10, 2024.
  • The finalized rule maintains limits of 4 nanograms per liter or parts per trillion (ppt) for PFOS and PFOA and includes new limits for four compounds.
  • While the final rule does not change the initial monitoring timelines, it does lengthen the MCL compliance deadline, allowing affected public water facilities five years to reduce the presence of PFAS compounds in their water.

The U.S. Environmental Protection Agency (EPA or Agency) announced the final rule for the National Primary Drinking Water Regulation (NPDWR) on April 10, 2024. The EPA evaluated more than 120,000 comments to the proposed rule that was issued more than a year ago. The final rule sets legally enforceable maximum contaminant levels for six per- and polyfluoroalkyl substances (PFAS).

The Rule in Brief

The six specific PFAS compounds covered include:

  • perfluorooctanoic acid (PFOA)
  • perfluorooctane sulfonic acid (PFOS)
  • perfluorononanoic acid (PFNA)
  • GenX chemicals: hexafluoropropylene oxide dimer acid (HFPO-DA)
  • perfluorohexane sulfonic acid (PFHxS)
  • perfluorobutane sulfonic acid (PFBS)

The Maximum Contaminant Levels (MCLs) and MCL Goals proposed for these chemicals are:

PFAS Compound

Final Legally Enforceable MCL

Final MCL Goal


4 parts per trillion (ppt)



4 ppt


PFNA, PFHxS, PFBS, GenX chemicals

10 ppt

10 ppt

Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS

1. Hazard Index (unitless)

1. Hazard Index (unitless)

Public water systems will have three years after the rule promulgation to comply with monitoring requirements, at which point they must begin reporting the results of their monitoring. The initial monitoring requirements will mandate four quarterly samples for larger systems serving populations over 10,000 people and biannual samples from smaller systems serving populations of 10,000 or fewer. Beginning five years after promulgation, if the levels of PFAS detected in these samples exceed the MCLs, public water systems must notify their served communities and take steps to reduce levels of PFAS in their drinking water.

The EPA does not specify how water systems must reduce levels of PFAS in their water supply or mandate a single technology to be used, but it has outlined the following as Best Available Technologies: granular activated carbon (GAC), anion exchange (AIX), nanofiltration (NF) and reverse osmosis (RO).

What Changed?

The EPA modified several provisions from the NPDWR proposed rule, such as adding new MCLs for individual chemicals previously only considered when combined with others and extending the deadline for compliance. The changes will primarily impact the implementation of the final rule without radically altering its intent, but the cumulative impacts will inform public water facilities and industry as they work to meet the standards.

Arguably the most drastic change to the standard was the addition of MCLs for four compounds that previously were targeted only when found in mixtures. The EPA set an MCL of 10 ppt for PFNA, PFHxS, PFBS, and "GenX Chemicals," a change advocated by many environmental groups during the comment period. However, the final rule also increases the threshold required for mixtures of PFAS compounds to trigger compliance actions by changing the institution of a 1.0 "Hazard Index MCL" on mixtures of one or more of PFHxS, PFNA, HFPO-DA and PFBS to mixtures of two or more of those compounds.

The EPA also clearly considered comments from public water works and industry as the Agency lengthened timelines for compliance and eased restrictions to some degree. Now, instead of requiring compliance for monitoring and reduction procedures within three years of rule promulgation, affected entities will have three years to complete initial monitoring and five years overall to implement solutions that reduce PFAS and also alert the public to the new levels and reduction efforts. The monitoring and remediation phases run concurrently. Under the final rule, compliance monitoring protocols will now go into effect when levels reach one-half final MCLs as compared to the previous trigger being set at one-third final MCLs. (For greater detail about the proposed rule and its background, see Holland & Knight's previous alert, "EPA Publishes Proposed PFAS Drinking Water Regulation," March 29, 2023.)  

What This Means for Public Water Works

All public water facilities will be subject to the monitoring conditions of the NPDWR, requiring monitoring be complete within three years of promulgation of this rule and continuing monitoring on a biannual or quarterly basis until the facilities reach one-half MCLs and are eligible for reduced monitoring conditions. Public water systems with PFAS contamination exceeding the MCLs will be required to take steps to reduce the presence of PFAS in their water supplies using best available practices within five years of promulgation. The EPA found that 6 percent to 10 percent of the 66,000 public drinking water systems subject to this rule are estimated to be out of compliance and will need to take remedial measures.

To alleviate the compliance costs for public water systems in small and/or disadvantaged communities, the EPA announced nearly $1 billion in newly available funding in conjunction with the National Drinking Water Standard. This funding falls under the same $9 billion investment from the Bipartisan Infrastructure Law (BIL) aimed at assisting drinking water facilities reduce the presence of PFAS and other emerging contaminants in their water. An additional $12 billion in BIL funding aimed at improving public water infrastructure to handle PFAS contamination will further reduce the regulatory burden placed on public water systems.

Despite this influx of funding, the mounting costs of compliance to address PFAS contamination have spurred concern among public water facilities. Although the EPA estimated the annual costs will total $1.5 billion in their comments on the proposed rule, one trade association shared a study that projects an annual cost of $3.8 billion, largely falling on the facilities and, in turn, the communities they serve. The report continues to estimate that "annual costs to households for removing PFAS from drinking water can range from $100 or more per year (for a population of over 1 million) to even $10,000 (for a population of less than 100)."

What This Means for States

Mounting public pressure and high-profile, multibillion-dollar water contamination cases prompted several states to act previously on PFAS MCLs in the absence of EPA regulatory activity. Over the last few years, multiple states – Maine, Massachusetts, Michigan, New Hampshire, New JerseyNew York, Pennsylvania, Rhode Island, Vermont, Washington and Wisconsin – established enforceable drinking water standards for certain PFAS in drinking water. Several states including Delaware and Virginia, are also in the process of considering MCLs for certain PFAS. Other states, such as Connecticut, Maryland and Oregon, have established non-enforceable "action levels" or drinking water guidelines. Some states such as California and Utah have begun monitoring programs in addition to EPA's Unregulated Contaminant Monitoring Rule. All of this adds another layer of complexity to the matter and confusion to consumers and regulated entities.

The foregoing patchwork approach has resulted in a wide range of concentrations for state-based PFAS drinking water standards or guidelines, ranging from 2 ppt (Connecticut "action level") to 400,000 ppt (Michigan enforceable standard) for certain compounds. Now that the EPA has finalized MCLs for six PFAS compounds, however, states must adhere to the federal standards as required by the SDWA if the federal standards are stricter. In practice, this means that states must yield to EPA implementation and enforcement of the MCLs within their jurisdiction or retain primacy by adopting new drinking standards that are at least as strict as the federal ones. States that decide to adopt new PFAS drinking water standards will need to ensure that their respective environmental agencies have the capacity, budgets and regulatory framework in place to safeguard against improper and ineffective implementation and enforcement.

What This Means for Industry

Given the high public costs of the final rule, we can anticipate attempts to offset these expenses by reducing the presence of upstream PFAS contamination. Comments from industry actors discussed the resounding implications MCLs will have on their businesses and usage of PFAS. Many industry actors reaffirmed their commitments to environmental stewardship and support for commonsense PFAS regulations, but urged the EPA to consider how increased cleanup costs could drive companies to areas where regulations are less stringent. As a result, industry commenters warn that the U.S. would lose jobs to offshoring while increasing global PFAS contamination. Companies also voiced concerns about the essential uses of PFAS that may be regulated offshore, once again detracting from the domestic economy or causing supply shortages as there is often no viable replacement for PFAS at this time. Further complicating the issue, many of the products that utilize PFAS in critical capacities are necessary for the clean energy transition, pitting two environmental goals squarely against one another.

What Comes Next?

The EPA's PFAS Strategic Roadmap has outlined the regulatory agenda for systematically tackling PFAS contamination. The EPA has largely followed the timeline presented in the roadmap, but an upcoming congressional deadline has fast-tracked the finalization of many Biden Administration rules, primarily regarding environmental policy. The Congressional Review Act allows lawmakers to swiftly reverse rules finalized and adopted 60 days before the end of a congressional session by allowing simple congressional majorities to overturn them. This strongly incentivizes the Agency to finalize high-priority regulations before reaching such a deadline. As a result, we will likely see a finalized rule designating certain PFAS as a "hazardous substance" under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) soon, lest the Agency risk such a rule being subject to a congressional overturn after the 2024 election.

Communities dealing with PFAS in their drinking water will also have to contend with residual impacts on wastewater processing facilities. The combination of the MCLs for six PFAS, the impending CERCLA "hazardous substance" designation, the proposed changes to the Resource Conservation and Recovery Act (RCRA) regulations, and potential Effluent Limitations Guidelines and testing requirements under the National Pollutant Discharge Elimination System (NPDES) will have significant impact on wastewater treatment operators, which will further compound the impact on communities.

To learn more about these topics, please contact the authors or a member of Holland & Knight's Emerging Contaminants and PFAS Team.

Information contained in this alert is for the general education and knowledge of our readers. It is not designed to be, and should not be used as, the sole source of information when analyzing and resolving a legal problem, and it should not be substituted for legal advice, which relies on a specific factual analysis. Moreover, the laws of each jurisdiction are different and are constantly changing. This information is not intended to create, and receipt of it does not constitute, an attorney-client relationship. If you have specific questions regarding a particular fact situation, we urge you to consult the authors of this publication, your Holland & Knight representative or other competent legal counsel.

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