What is the EPA PFAS drinking water limit?

The EPA finalized MCLs of 4 parts per trillion (ppt) for PFOA and PFOS individually, and 10 ppt each for PFNA, PFHxS, and HFPO-DA (GenX). A mixture hazard index of 1.0 applies to combinations of PFNA, PFHxS, PFBA, and PFBS. These are the first legally enforceable federal limits for any PFAS in drinking water, finalized in April 2024.

When do utilities need to comply with PFAS rules?

Public water systems must complete initial PFAS monitoring by 2027. They must come into full compliance, meaning reducing PFAS to below the new MCLs, by 2029. Utilities that detect PFAS above MCLs during monitoring must notify customers, but they have until 2029 to install treatment.

Does my water have PFAS?

Check the EWG Tap Water Database at ewg.org/tapwater with your zip code. It compiles utility testing data. Your annual Consumer Confidence Report (CCR) should also report any PFAS detected above the reporting limit. Private well owners need to test independently, as the 2024 rule covers only public water systems serving 25 or more people.

What removes PFAS from drinking water?

NSF/ANSI 58-certified reverse osmosis systems remove 90-99% of PFOA and PFOS. Filters certified to NSF P473 have been independently tested for PFAS reduction. Granular activated carbon reduces some PFAS but not consistently for all compounds. Verify the specific NSF certification number on any filter you purchase.

Is my city water being tested for PFAS?

All public water systems serving 25 or more people must complete initial PFAS monitoring under the 2024 rule, with testing required by 2027. Many utilities in states with their own PFAS programs (Michigan, California, New York) have been testing since 2019-2021. The EWG Tap Water Database shows which utilities have detected PFAS and at what levels.

The EPA's 2024 PFAS Drinking Water Rule: What It Means for Your Tap

For decades, PFAS in drinking water had no federal limit. That changed on April 10, 2024, when the EPA finalized the first legally enforceable maximum contaminant levels (MCLs) for PFAS compounds in public water supplies.

This is a significant shift. It means utilities that exceed the new limits now have a legal obligation to fix the problem, not just report it.

What the Rule Sets

The 2024 rule establishes MCLs for six PFAS compounds.

PFOA gets a 4 ppt (parts per trillion, equivalent to nanograms per liter) MCL. PFOS gets the same, 4 ppt. Both are long-chain PFAS that have been manufactured and used in the US for decades, and both are now phased out of domestic production.

PFNA, PFHxS, and HFPO-DA (also called GenX) each get a 10 ppt MCL. GenX was developed as a replacement for PFOA and has been found in North Carolina waterways near DuPont/Chemours manufacturing facilities.

A mixture MCL applies to combinations of PFNA, PFHxS, PFBA, and PFBS. Utilities must calculate a hazard index, and it cannot exceed 1.0. This prevents utilities from complying with individual compound limits while allowing concerning mixtures.

The maximum contaminant level goal (MCLG) for both PFOA and PFOS is zero. An MCLG of zero means the EPA considers no exposure to be without some associated risk. The MCL (4 ppt) is the technically and economically feasible limit, not a “safe” level.

Who Must Comply

The rule covers all public water systems serving 25 or more people. That’s approximately 66,000 community water systems across the US.

Private wells are not covered. If you’re on a private well, the 2024 rule doesn’t require your water to be tested. Testing is voluntary.

The Compliance Timeline

Utilities have until 2027 to complete initial monitoring. By that point, every covered water system must test for the six regulated PFAS compounds.

Utilities that find PFAS above the MCLs must notify customers. That notification requirement kicks in as soon as monitoring confirms the exceedance, not in 2029.

The 2029 deadline is for treatment, the actual reduction of PFAS to below MCLs. Utilities have five years from the final rule (2024 to 2029) to install granular activated carbon systems, high-pressure membrane filtration, or other EPA-approved treatment methods.

The EPA estimates approximately 6,000 to 10,000 public water systems have PFAS above the new MCLs. About 100 million Americans are served by these systems. The estimated national compliance cost is $1.5 to $3 billion per year, according to EPA modeling.

What This Means for You Before 2029

If your utility detects PFAS above the MCL in monitoring, they’re required to tell you. But they have until 2029 to actually treat the water.

That’s a meaningful gap. A customer notification doesn’t change the PFAS concentration in the water. Point-of-use treatment is the consumer’s option during the compliance period.

For utilities that already tested under state programs (Michigan, California, New York all have their own PFAS monitoring programs with earlier timelines), some customers have known about PFAS in their water since 2019 or 2020. Many are already using point-of-use filtration.

What Removes PFAS

An NSF/ANSI 58-certified reverse osmosis system removes 90-99% of PFOA and PFOS per independent testing. The certification requires documented reduction rates, not just a marketing claim.

NSF P473 is a separate certification specifically for PFAS reduction. Several Clearly Filtered products hold P473 certification. This certification covers PFOA and PFOS reduction from filters that aren’t RO systems.

Granular activated carbon (GAC) is what most utilities will use for large-scale treatment. At the utility level, GAC is practical and cost-effective. At the household level, GAC reduces some PFAS but inconsistently, and not for all compounds. A properly designed GAC household system can work, but the certification documentation is harder to verify than NSF 58.

Standard carbon pitcher filters (Brita, PUR, ZeroWater) don’t reduce PFAS. Their certifications cover taste and odor or heavy metals, not PFAS.

Checking Your Utility

The EWG Tap Water Database is the most accessible tool for consumers. Enter your zip code to see what your utility has detected and at what levels. It pulls from utility monitoring data that systems are required to submit.

For states with independent PFAS programs, state environmental agency websites often have more current data than EWG, which may lag by 6-12 months on updates.

Your annual Consumer Confidence Report (CCR) will report PFAS if detected above reporting thresholds. See how to read your water quality report for guidance on finding your CCR and understanding the numbers.

If your utility has detected PFAS at any level, an NSF 58-certified RO or NSF P473-certified filter gives you documented protection now, regardless of where your utility is on the compliance timeline. Read the full PFAS contaminant guide and the PFAS removal how-to for more on specific treatment options.