National Primary Drinking Water Regulations for PFAS

EPA Unveils National Primary Drinkng Water Regulations for Six PFAS

On April 10, 2024, the United States Environmental Protection Agency (EPA) announced National Primary Drinking Water Regulations (NPDWRs) for six per- and polyfluoroalkyl substances (PFAS). The six PFAS are: perfluorooctanoic acid (PFOA); perfluorooctane sulfonic acid (PFOS); perfluorohexane sulfonic acid (PFHxS); perfluorononanoic acid (PFNA); hexafluoropropylene oxide dimer acid (HFPO-DA); and mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and perfluorobutane sulfonic acid (PFBS).

What are PFAS?

PFAS, frequently called “forever chemicals,” are a class of chemicals first developed in 1938. Since that time, PFAS have become seemingly ubiquitous, and their uses range from firefighting foams to the coating on kitchen pots and pans, from adhesives to personal care products. Due to their chemical composition, these substances do not easily degrade in the environment: in many instances they were designed to be heat and water resistant. Given their presence in a wide array of household products, they have been detected in water systems across the country. PFAS have been linked to multiple cancers, liver and heart impacts in adults, and immune and developmental impacts in infants and children.

What Do the NPDWRs Mean?

The Safe Drinking Water Act allows the EPA to establish NPDWRs to regulate emerging contaminants that can be dangerous in drinking water. The statute allows the EPA to act according to the “best available” science and data. Pursuant to the Safe Drinking Water Act, the EPA may establish Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs).  The MCLs are a legally enforceable limit for listed contaminants, while the MCLGs are non-enforceable levels below which there is no known or expected health risk. The MCLs and MCLGs for the six PFAS are:

Compound Final MCLG Final MCL
PFOA Zero 4.0 ppt*
PFOS Zero 4.0 ppt
PFHxS 10 ppt 10 ppt
PFNA 10 ppt 10 ppt
HFPO-DA 10 ppt 10 ppt
Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS 1 (unitless)

Hazard Index**

1 (unitless)

Hazard Index

*PPT = parts per trillion.

**The hazard index reflects the need to account for the differing levels of the combined and co-occurring levels of each contaminant in a given PFAS mixture.


Who do the NPDWRs Apply to?

NPDWRs, broadly speaking, apply to public water systems (PWSs), which include both community water systems (CWSs) and non-transient, non-community water systems (NTNCWSs). A PWS provides water to the public for consumption through pipes or other conveyances, “if such system has at least fifteen service connections or regularly serves an average of at least twenty-five individuals daily at least 60 days out of the year.” A CWS is a “PWS which serves at least fifteen service connections used by year-round residents or regularly serves at least twenty-five year round residents.” A NTNCWS is “a PWS that is not a [CWS] and that regularly serves at least 25 of the same persons over 6 months per year.”

What Obligations do PWSs Have under the New NPDWRs?

PWSs will have three years to complete the initial monitoring requirements. For systems serving over 10,000 people this monitoring will require quarterly sampling withing a 12-month period for the listed PFAS. For systems serving less than 10,000 people, sampling would only need to occur twice within a 12-month period, with each sampling occurring over 90 days apart. The initial monitoring requirements may be satisfied by using previously collected data. Once the initial monitoring requirements are met, PWSs must continue with compliance monitoring to ensure they do not exceed MCLs.

For those PWSs whose monitoring reveals MCL exceedances, they will have until 2029 to implement solutions to reduce those levels. Beginning in 2029, PWSs with MCL exceedances will be required to take action to correct them. Further, the PWSs will be required to provide notice of the violation to the public.

The new regulations do not set forth requirements on how PWSs must remove detected contaminants. The EPA stated that it kept the rule flexible so that each PWS may select treatment options that work best for it.

Will Funding be Available to Implement Testing and Control Measures?

Along with the publication of the new NPDWRs, the EPA also announced that it was making almost $1 billion available for states and territories under the Emerging Contaminants in Small or Disadvantaged Communities Grant Program. These funds can be used for either initial testing or treatment, and they are available to PWSs as and private owners of wells. This $1 billion is part of $9 billion made available under the Bipartisan Infrastructure Law for communities whose drinking water is impacted by PFAS. A further $12 billion is available for communities to make general drinking water improvements under the BIL. In addition to this funding, disadvantaged communities may utilize the EPA’s free Water Technical Assistance Program that provides support in developing plans for capital improvements, building technical capacity, and applying for grants.


The pre-publication Federal Register Notice is available here

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