PFAS in Tap Water: What "Forever Chemicals" Mean for Your Drinking Water
PFAS — "forever chemicals" — have been detected in nearly half of US tap water. Here's what the science says, where regulation stands after the 2025 rollback, and what you can actually do about it.
PFAS are invisible, odorless, and nearly indestructible — that's why they're called "forever chemicals." A 2023 USGS study found that at least 45% of US tap water contains at least one PFAS compound. The EPA finalized the first-ever federal limits in 2024 — then partially rolled them back in 2025.
What that means for your drinking water, whether you're affected, and what you can do about it: that's what this guide covers.
What Are PFAS?
PFAS stands for per- and polyfluoroalkyl substances — a group of more than 14,000 synthetic chemicals that have been manufactured and used since the 1940s. You'll find them in non-stick coatings (Teflon), water-resistant textiles, food packaging, firefighting foam, and countless industrial processes.
What makes PFAS unique is the carbon-fluorine bond at their core — one of the strongest bonds in chemistry. This is what makes them so useful in manufacturing and so persistent in the environment. PFAS don't meaningfully break down in soil, water, or the human body. They've been detected in the blood of virtually all Americans.
The six PFAS compounds that the EPA has targeted for regulation are: PFOA, PFOS, PFHxS, PFNA, GenX (HFPO-DA), and PFBS (as part of the Hazard Index). Each has a different industrial history, a different half-life in the body, and a slightly different risk profile — but all share the fundamental problem of persistence.
How Do PFAS Get Into Tap Water?
Unlike arsenic (which occurs naturally in rock) or lead (which leaches from household plumbing), PFAS contamination is primarily a source-water and treatment problem. It enters the water supply before it reaches your home.
The main pathways are industrial sites that manufactured or used PFAS, military bases and airports (where PFAS-containing firefighting foam, known as AFFF, was used for decades), wastewater treatment plants (which can't fully remove PFAS from household and industrial effluent), and landfills and composting facilities.
From these sources, PFAS migrates through surface water and groundwater into municipal drinking water supplies. The USGS study mapped the pattern: contamination concentrates in urban areas and near known PFAS sources. The probability of finding PFAS in tap water is roughly 75% in urban areas and 25% in rural areas. Particularly affected regions include the Great Plains, Great Lakes, Eastern Seaboard, and Central and Southern California.
This matters because it means PFAS contamination isn't something you can fix with better home plumbing. It requires action at the water treatment level — or filtration at the point of use.
Health Effects of PFAS
The research is ongoing, but the evidence to date is concerning enough that the EPA decided to set binding limits.
Documented and probable health effects from PFAS exposure above certain thresholds include:
- Cancer risk — kidney and testicular cancer are the best-documented associations, particularly for PFOA and PFOS
- Elevated cholesterol levels
- Liver damage
- Thyroid disease
- Immune system effects — reduced vaccine effectiveness, particularly in children
- Fertility and developmental effects
Important context: most studies reference higher exposure levels or occupational exposure. The risk from typical drinking water concentrations in the US is harder to quantify — but the EPA determined in 2024 that the evidence was sufficient to set enforceable limits.
PFAS accumulate in the body over years. The half-life of PFOS in human blood is approximately 5 years — meaning even after exposure stops, it takes years for levels to drop significantly. This cumulative nature is why long-term, low-level exposure matters more than occasional contact.
EPA Regulation: What Happened in 2024 and 2025
The regulatory timeline for PFAS in drinking water has been unusually turbulent. Here's where things stand.
April 2024: The EPA published the first-ever National Primary Drinking Water Regulation for PFAS. It set Maximum Contaminant Levels for six compounds:
- PFOA: 4 parts per trillion (ppt)
- PFOS: 4 ppt
- PFHxS: 10 ppt
- PFNA: 10 ppt
- GenX (HFPO-DA): 10 ppt
- Plus a "Hazard Index" for mixtures of PFHxS, PFNA, GenX, and PFBS
Water utilities had until 2027 to begin testing and until 2029 to implement treatment solutions.
May 2025: The EPA announced a partial rollback of the regulation:
- PFOA and PFOS: Limits remain in place, but compliance timelines were extended and an exemption framework was introduced
- PFHxS, PFNA, GenX, and the Hazard Index: The EPA moved to revoke the regulation for these four and reassess the regulatory decisions
Current status: The situation is in flux. The PFOA and PFOS limits formally remain, but the enforcement timeline is unclear. For the other four compounds, there are no binding federal limits for now.
State-level standards: Eleven states have adopted their own PFAS drinking water standards, some stricter than the (partially rolled back) federal standards: Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Washington, and Wisconsin. If you live in one of these states, state regulations may provide stronger protection than the current federal framework.
What this means in practice: whether and how strictly PFAS is regulated in your water currently depends on which state you live in. Look up your city on TapWater.org to see whether PFAS data is available for your water system.
How to Find Out If Your Water Has PFAS
Start with your Consumer Confidence Report (CCR). Your water utility must publish PFAS test results starting in 2027 under the federal rule. Many utilities are already testing voluntarily. Check your CCR or look up your city on TapWater.org to see what data is available.
Check UCMR 5 data. The EPA conducted a nationwide testing round under the Unregulated Contaminant Monitoring Rule 5 (2023–2025). Results are available through the EPA or the EWG Tap Water Database.
Test your own water. If your utility hasn't tested for PFAS yet — or if you're on a private well — you can order a lab test. PFAS testing is significantly more expensive than standard water tests: expect to pay $85–$300 depending on the provider and scope. Standard test strips can't detect PFAS. See our best water test kits guide for options.
Context for interpreting results: The EPA's PFAS limits are in the parts-per-trillion range — extraordinarily low. For comparison, the arsenic limit is 10 parts per billion, which is 1,000 times higher. Detecting PFAS in your water doesn't automatically mean an acute health risk, but it does signal that filtration is worth considering.
Which Filters Remove PFAS?
Not all filtration methods are equal when it comes to PFAS. Here's what works and what doesn't.
What works
Reverse Osmosis (RO): Removes 90–99% of PFAS compounds across the board. This is the most effective home treatment method. Under-sink RO systems cost $150–$500 and are the recommended approach for households concerned about PFAS.
Granular Activated Carbon (GAC): Effective at removing most long-chain PFAS (PFOA, PFOS) but less reliable for short-chain compounds (GenX, PFBS). Some higher-end pitcher filters and refrigerator filters use GAC — but effectiveness varies widely by product and filter replacement interval.
Ion Exchange Filters: Effective across a broad spectrum of PFAS compounds. Increasingly used in municipal treatment plants as well as point-of-use home systems.
What does NOT work
- Standard Brita pitchers with basic carbon filters do not reliably remove PFAS
- Boiling has no effect on PFAS — just like with arsenic and lead, boiling can actually increase concentrations as water evaporates
- Water softeners have no effect on PFAS
What to look for
Check for NSF/ANSI Standard 53 (with explicit PFAS listing) or NSF/ANSI Standard 58 (for RO systems). Not every filter that advertises "PFAS removal" is actually certified — verify the certification at nsf.org. And remember that filter cartridges must be replaced on schedule. PFAS removal performance degrades over time as the filter media becomes saturated.
A note on disposal: Used PFAS filters contain concentrated PFAS. Check with your local waste authority on proper disposal to keep the chemicals from re-entering the environment.
The Bigger Picture
PFAS in drinking water is a systemic issue, not an individual failure. These chemicals were mass-produced and used for decades before the health risks were fully understood. The regulatory landscape is in motion — at both the federal and state level — and what applies today may change in the coming years.
What you can do as an individual: stay informed, know your water, and filter if warranted. A reverse osmosis system at your drinking water tap is the most pragmatic solution for households that are concerned. It's effective, relatively affordable, and doesn't require you to wait for regulatory outcomes.
For the latest PFAS data on your city: check your city's water quality on TapWater.org.
Further reading: PFOA · PFOS · PFHxS · PFNA · GenX · Lead in Tap Water · Best Water Test Kits · Check Your City's Water Quality
TapWater.org
Our mission is to bring transparency to US drinking water quality. We compile official EPA data and municipal reports so you can make informed decisions about the water you drink.
Learn more about us →You Might Also Like
Is Tap Water Safe to Drink? What You Actually Need to Know (2026)
For most Americans, yes — US tap water is among the safest in the world. But the real question is whether your tap water, in your home, is safe right now.
Is Hot Tap Water Safe to Drink?
Filling the kettle from the hot tap to save time? That's a lead risk, not a time-saver. Here's the EPA's actual guidance, who it applies to, and the easy habit change that removes the risk entirely.