What do the EPA’s new Maximum Contaminant Levels for PFAS mean for drinking water suppliers?

By Jeffrey Holden, Senior Project Manager/Engineer

The EPA released new maximum contaminant levels for PFAS chemicals – what do they mean and how do drinking water suppliers stay in compliance?

In spring of 2024, the Environmental Protection Agency (EPA) announced the Final PFAS National Primary Drinking Water Regulation, which introduced new maximum contaminant levels (MCLs) for PFAS chemicals.

PFAS, or per- and poly-fluoroalkyl substances, are a family of chemicals that can pose a threat to human health. Due to their unique properties, PFAS have been used for decades in many commercial and consumer products, including certain firefighting foams, non-stick coatings, stain-resistant products, food packaging, and personal care products. As a result, they are present in a number of drinking water supplies. To protect the public, the EPA has established strict limits on concentrations of several PFAS chemicals, as summarized in the chart, below.

PFAS MCLs are provided in units of parts per trillion (ppt) which is quite low compared to MCLs established for other drinking water contaminants. The new regulations are designed to keep drinking water safe for the public. The ability to legally enforce these limits will enable the EPA to track water suppliers as they sample and measure PFAS contaminants. Understanding these limits and how to track them will help your business or municipality not only stay in compliance, but also remain at the forefront of PFAS regulatory advancements.

The EPA ruling went into effect on June 25, 2024 for the following six chemicals:

Chemical	Maximum Contaminant Levels
PFOA	4.0 ppt
PFOS	4.0 ppt
PFHxS	10 ppt
PFNA	10 ppt
GenX	10 ppt
Mixtures of two or more: PFHxS, PFNA, GenX, and PFBS	Hazard Index of 1

The chart above lists five PFAS chemicals, with the sixth category including a mix of two or more specific contaminants. The column to the right identifies the maximum contaminant level for the corresponding chemical in parts per trillion. This signifies the total maximum amount of a contaminant allowed in a liter of water.

After understanding these new limits, we can begin testing treated water for compliance with these standards. The EPA requires sampling on a quarterly basis. The average of testing from four consecutive quarters gives the Running Annual Average (RAA), which is the number value EPA considers for evaluating compliance. The final ruling allows water suppliers three years, until 2027, to have a full year’s worth of records on file. The EPA also requires solutions for PFAS MCL violations to be fully implemented within five years, or by April 26, 2029.

A water system is considered out of compliance when the RAA exceeds the chemical’s MCL. The EPA also requires continued monitoring, although the frequency will depend on contaminant level.

All regulated PFAS detected as part of this monitoring program must also be included in the Consumer Confidence Reports (CCR) that suppliers prepare and deliver to their customers. If there is a violation of any kind, you must take measures to come into compliance. You must report all data from initial and compliance monitoring to the state, including all results, the current RAA, and any violations of the MCLs.

While the EPA does not require specific mitigation efforts, there are some with more success than others depending on the water system your organization has. PFAS treatment systems, alternative water sourcing, or blending are all options to help address MCL violations.

Disadvantaged communities and small systems can also access the Infrastructure Investment and Jobs Act (IIJA) funding to help pay for treatment system installation.

The EPA is focused on improving public health related to PFAS contamination. It’s important that your business or municipality understands the EPA’s new MCL rulings to remain in compliance and to mitigate PFAS contaminants when necessary.

To discuss the EPA’s Final PFAS National Primary Drinking Water Regulation and how it impacts your organization, contact me.