EPA Sets Stringent Federal PFAS Drinking Water Limits


The U.S. Environmental Protection Agency recently published a final rule creating a legally enforceable drinking water standard for six per- and poly-fluoroalkyl substances under the Safe Drinking Water Act that will affect millions of people and thousands of manufacturing and other facilities that supply their own water in Connecticut and nationwide.   

At least 50 manufacturing sites in Connecticut (and many more across the northeast) are subject to this new rule. 

While the rule specifically addresses PFAS in drinking water, it will have a wide- and far-reaching impact with respect to the regulation of PFAS generally, particularly as EPA and state environmental agencies are likely to rely on the new drinking water standards as support for regulating PFAS in other contexts.  

In addition, the new rule will continue to spur PFAS-related litigation.

Health, Environmental Concerns

For those that are unfamiliar, PFAS are thousands of “emerging contaminants” at the center of increasing health and environmental concerns.  

PFAS have been commonly used in numerous commercial and industrial applications where their resistance to water, heat, and stains are beneficial.  

Until now, PFAS in drinking water were regulated by an incomplete and inconsistent federal and state-by-state patchwork of regulation.

As result, PFAS have become ubiquitous in the environment and are now commonly detected in drinking water globally.  

Until now, PFAS in drinking water were regulated by an incomplete and inconsistent federal and state-by-state patchwork of regulation and non-enforceable administrative guidance.

New Federal Standards

Under the SDWA, the EPA has set the first federally enforceable standards for six PFAS and certain PFAS mixtures in drinking water with stringent maximum contaminant levels and MCL Goals (see table below).   

These near-zero standards and goals represent the lowest concentrations at which labs can reliably measure these substances in water.  

Final MCL (Enforceable)
Parts Per Trillion (ppt)
Final MCL Goal (Non-Enforceable)
PFOA4 ppt0 ppt
PFOS4 ppt0 ppt
PFHxS10 ppt10 ppt
PFNA10 ppt 10 ppt
HFPO-DA (GenX Chemicals10 ppt10 ppt
Mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PPFBSHazard Index 1 (unitless)Hazard Index 1 (unitless)

Notably, important aspirational MCLGs for PFOA and PFOS are zero as EPA maintains there is no “safe” level of consumption.  

Connecticut and other states may also regulate PFAS in drinking water but any standards must be at least as stringent as these new federal standards.

The final rule partially mirrors EPA’s proposed rule published in March 2023 with some key adjustments, particularly the addition of dedicated MCLs and MCLGs for PFHxS, PFNA and HFPO-DA (a/k/a GenX) and a “hazard index”  for mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS.  

Staggered Implementation

The new rule will apply to two of the three classes of Public Water Systems regulated under the SDWA: (i) Community Water Systems that serve at least 25 year-round residents or 15 connections used by year-round residents; and (ii) Non-Transient Non-Community Water Systems that serve at least the same 25 people for at least six months per year.  

Notably, CWSs, and NTNCWs include many manufacturing and industrial facilities that operate their own drinking water wells. 

PFAS Federal Sampling and Mitigation time frames

CWSs and NTNCWs subject to EPA’s new requirements must perform the following within the timeframes noted:

Notably, the regulations do not specify any particular methods for removing PFAS from drinking water, so regulated PWSs will have flexibility to use treatment technologies currently available and/or under development for point-of-entry or point-of-use removal (e.g., granular activated carbon filtration, nanofiltration, reverse osmosis, anion exchange systems).  

Regulated PWSs may also blend water sources to reduce PFAS concentrations or pursue developing a new water source.

Preparing for PFAS Regulation

Under existing SDWA regulations, regulated PWSs are already required to comply with MCLs and other standards for a variety of constituents of concern, including certain metals (e.g., lead, copper, arsenic), chemicals (e.g., nitrate, nitrite), and microbials (e.g., total coliform).  

PWSs now have an opportunity, with this new PFAS rule, to assess their overall operating procedures and compliance with the SDWA, including with respect to these “traditional” contaminants.

However, the new PFAS rule is a significant departure from existing SDWA requirements because the PFAS enforceable standards are so low (nearly non-detect) and the cost of mitigating even slight MCL exceedances will be so high (estimated in the billions per year nationally). 

It is critical for manufacturers and other regulated entities to evaluate their drinking water source.

To jumpstart this effort, CWSs and NTNCWs should consider developing a risk management plan specific to their water source, operations, and potential PFAS-related risks and liabilities including, not only compliance with applicable regulatory requirements, but also evaluating potential third party claims.

In addition, it is critical for manufacturers (including producers of foods and beverages that use water as an ingredient or in their processes) and other regulated entities to evaluate their drinking water source and the potential risks related to PFAS generally.  

In light of the evolving regulatory framework related to PFAS and the ever-increasing threat of PFAS-related litigation, any internal risk assessment should be carefully conducted through in-house or external legal counsel. 

Alfredo Fernández and Scarlett Lara-Alcantara, Shipman & Goodwin

About the authors: Alfredo Fernández is a partner at Shipman & Goodwin LLP, serving as the chair of the firm’s manufacturing team and practicing in the firm’s national environmental and international trade practices. Scarlett Lara-Alcantara is an associate in Shipman’s real estate, environmental, energy, and construction practice group.

For more information about Shipman’s manufacturing practice, please contact Alfredo Fernández (860.251.5353).


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