On April 10, 2024, the EPA made history. After decades of studying, debating, and delaying, the agency established the first-ever legally enforceable limits on PFAS in drinking water. These Maximum Contaminant Levels (MCLs) will eventually require every public water system in America to test for PFAS and treat water that exceeds the new standards.
But "eventually" is the key word. The compliance timeline stretches to 2029, and millions of Americans will continue drinking PFAS-contaminated water in the interim. This article explains exactly what the new rules require, when they take effect, and what you should do right now.
The EPA established limits covering six specific PFAS compounds: individual MCLs for five, plus a mixture limit that also covers PFBS:
PFOA (Perfluorooctanoic Acid): 4.0 parts per trillion (ppt) The "Teflon chemical" – one of the most studied and toxic PFAS compounds. The EPA set its health goal (MCLG) at zero.
PFOS (Perfluorooctane Sulfonate): 4.0 ppt The "Scotchgard chemical" – equally toxic and persistent. Found in firefighting foam used at military bases and airports nationwide.
PFNA (Perfluorononanoic Acid): 10 ppt A nine-carbon PFAS compound linked to developmental toxicity and immune effects.
PFHxS (Perfluorohexane Sulfonic Acid): 10 ppt A six-carbon sulfonate found in firefighting foam alongside PFOS. It is one of the slowest PFAS to leave the human body, with a half-life of five years or more.
HFPO-DA (GenX Chemicals): 10 ppt Manufactured by Chemours as a replacement for PFOA. Major contamination source in North Carolina's Cape Fear River region.
For combinations of PFHxS, PFNA, HFPO-DA, and PFBS, the EPA introduced a Hazard Index approach. The Hazard Index cannot exceed 1.0, calculated by summing the ratio of each compound's measured level to its health-based reference value.
This is important because PFAS compounds often occur together, and their combined effects may be greater than any single compound alone.
Four parts per trillion is an extraordinarily small number. To put it in perspective:
The EPA set the health goal for PFOA and PFOS at zero, meaning no level is considered risk-free; 4 ppt is about the lowest level labs can reliably measure. For context, the previous EPA health advisory for PFOA was 70 ppt – the new standard is 17.5 times stricter.
All community water systems and non-transient non-community water systems, regardless of size, must complete initial monitoring for the regulated PFAS by 2027. Smaller groundwater systems (10,000 people or fewer) sample less often.
Testing frequency: Initially quarterly for most systems, then potentially reduced to annual or once every three years for systems with consistently low or non-detect results.
Under the rule, water utilities must:
Water systems exceeding MCLs must implement one of several solutions:
The EPA's regulations only apply to public water systems. If your home uses a private well, there is no federal requirement to test for PFAS. Given that private wells near military bases, industrial sites, and airports may have very high PFAS levels, this is a significant gap.
If you're on a private well, consider testing through a certified lab. A PFAS water test typically costs a few hundred dollars; for example, empowerDX sells a 29-PFAS mail-in kit for $299.
The 2024 rule covers small community systems on the same 2029 timeline, but EPA's UCMR 5 survey only tested systems serving 3,300 or more people plus a representative sample of about 800 smaller systems. So most small systems had no federal PFAS data before the new rule's monitoring began. Some states have imposed their own requirements on smaller systems.
These drinking water standards do not address PFAS in food, cosmetics, textiles, or other consumer products. Separate regulatory actions are underway for those exposure pathways, but progress is slow.
Over 12,000 PFAS compounds exist, but the EPA has set limits for only six. Many "replacement" PFAS – developed after older compounds were phased out – remain unregulated, and in May 2026 the EPA proposed dropping four of the six limits rather than adding more.
Several states enacted their own PFAS standards before the federal rule. Most are less strict than the federal 4 ppt limits for PFOA and PFOS, though some cover compounds the federal rule doesn't:
State standards: - New Jersey: 13 ppt PFNA, 14 ppt PFOA, 13 ppt PFOS - New Hampshire: 12 ppt PFOA, 15 ppt PFOS, 18 ppt PFHxS, 11 ppt PFNA - Vermont: 20 ppt (sum of five PFAS) - Maine: 20 ppt (sum of six PFAS) - California: Notification levels of 5.1 ppt PFOA, 6.5 ppt PFOS
Aligned with federal: Most other states are adopting the EPA's MCLs as their standards.
When federal and state standards differ, the stricter standard applies. If your state has a 12 ppt limit for PFOA and the federal limit is 4 ppt, your utility must meet the 4 ppt federal standard.
The EPA estimates the total cost of implementing the new standards at $1.5 billion annually across all affected water systems. This cost will ultimately be borne by:
How much PFAS treatment adds to a household water bill varies widely. It depends on:
The compliance deadline is years away. During that time, you and your family may be drinking water that exceeds the new safety standards. Take action now:
Check your exposure: Use our free ZIP code lookup to see current PFAS testing data for your water system.
A PFAS-removing water filter provides immediate protection regardless of your utility's compliance timeline. Pitcher filters certified to NSF/ANSI 53 for PFOA/PFOS cost well under $100.
Sign up for your water utility's notifications. Under the new rules, they must inform you of PFAS detections. You can also check the EPA's UCMR 5 data directly.
If your water exceeds the new limits, you have the right to:
The final rule was published in April 2024. Water systems must complete initial monitoring by 2027 and achieve compliance by 2029 (2031 for PFOA and PFOS under EPA's May 2026 proposal). The MCLs themselves are not enforceable until the compliance date, so a system testing above them now is expected to plan treatment before then.
Your water utility must report its PFAS results in its annual water quality report starting in 2027 and achieve compliance by 2029 (2031 for PFOA/PFOS if EPA's proposal is finalized). In the meantime, the EPA notes that certified home filters, such as reverse osmosis and activated carbon units, can reduce PFAS in drinking and cooking water.
No. The EPA's MCLs only apply to public water systems. Private well owners are responsible for their own testing and treatment. If you're on a private well near a known contamination source, testing is strongly recommended.
Yes, in either direction. In May 2026 the EPA proposed rescinding the limits for PFNA, PFHxS, GenX and the Hazard Index mixture and letting systems extend PFOA/PFOS compliance to 2031, while keeping the 4 ppt PFOA and PFOS limits. Those proposals are not final, so check for updates.
Some scientists and advocacy groups argue that no level of PFAS is truly safe and that the 4 ppt standard, while a major improvement, may still allow harmful exposures. The EPA set the MCLs at levels it considers feasible to achieve with current treatment technology while providing a meaningful public health benefit.
You can Check your water quality by zip code to see if your area is affected. If you're looking for solutions, Find water filters that remove PFAS certified for removal. Check your state's water quality to compare contamination levels across the country.
Check your water now. Enter your zip code at KnowYourExposure.com to see what contaminants have been detected in your local water supply – including PFAS, lead, and other regulated compounds.