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 MCLs for six specific PFAS compounds:
PFOA (Perfluorooctanoic Acid): 4.0 parts per trillion (ppt) The "Teflon chemical" – one of the most studied and toxic PFAS compounds. The 4 ppt limit is the lowest enforceable standard the EPA has ever set for any contaminant.
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 compound used as a replacement for PFOS. Despite being marketed as "safer," research shows significant toxicity.
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 fact that PFAS causes measurable health effects at this concentration underscores just how toxic these chemicals are. For context, the previous EPA health advisory for PFOA was 70 ppt – the new standard is 17.5 times stricter.
All public water systems serving 3,300 or more people must test for the six regulated PFAS compounds. Smaller systems that the EPA has specifically identified must also test.
Testing frequency: Initially quarterly, then potentially reduced to annual for systems with consistently low or non-detect results.
When PFAS is detected above MCLs, 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. The cost is typically $149-$300 for a comprehensive PFAS panel.
Water systems serving fewer than 3,300 people have extended timelines and may not be required to test under UCMR 5. 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. The agency has signaled that additional regulations may follow, but no timeline has been announced.
Several states have enacted PFAS standards that are stricter than the federal MCLs:
Stricter than federal: - 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:
The EPA estimates that for most households, the cost of PFAS treatment will add $5 to $15 per month to water bills. This figure varies significantly based 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. Options start at $90 for a certified pitcher filter.
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 monitoring by 2027 and achieve compliance by 2029. However, the standards are enforceable now – any system that tests above the MCLs must begin working toward compliance.
Your water utility must notify you, develop a treatment plan, and achieve compliance by 2029. In the meantime, the EPA recommends using a certified home water filter, especially for 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. The EPA reviews MCLs periodically and can make them stricter if new science warrants it. Given the rapid pace of PFAS research, future adjustments are possible. The standards are unlikely to become less strict.
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.