PFAS in Tap Water: How to Find Out If Yours Has It

Published October 7, 2026. Every claim is checked against the sources listed at the end of this page. How we research.

How common is PFAS in US tap water?

PFAS (per- and polyfluoroalkyl substances) are thousands of man-made chemicals used in nonstick coatings, stain-resistant fabrics, food packaging and some firefighting foams. They break down very slowly, which is why they are called “forever chemicals,” and they can reach drinking water sources from factories, airports, military bases, landfills and wastewater.

Two large federal efforts give a sense of scale. In 2023 the US Geological Survey (USGS) tested tap water from 716 locations for 32 PFAS and estimated that at least 45% of the nation’s tap water has one or more types. It found PFAS at similar levels in public supplies and private wells, with most detections in urban areas around the Great Plains, Great Lakes, Eastern Seaboard and central and southern California.

The second effort is the EPA’s fifth Unregulated Contaminant Monitoring Rule, known as UCMR 5. It required every community water system serving 3,300 or more people, plus a representative sample of smaller ones, to test for 29 PFAS and lithium during one 12-month period between 2023 and 2025. The EPA released the final data on August 27, 2026: just under 2 million results from more than 10,000 public water systems.

An April 2026 analysis of the UCMR 5 data by Pace Analytical found that about 8% of participating systems reported PFOA above 4 ppt and 8.9% reported PFOS above 4 ppt. Other regulated PFAS were rarely above their limits: about 0.7% of systems for PFHxS and about 0.1% for PFNA. In its final release, the EPA said 7.8% of water systems would have a running annual average above the limit for PFOA or PFOS. Put simply, most systems are below the limits, but a meaningful minority are not, and you cannot tell which group yours is in without looking.

Step 1: Search the EPA’s UCMR 5 Data Finder

This is the fastest free check for most people on city water. The UCMR 5 Data Finder lets you filter results by water system name or ID, state, system size, contaminant and source water type.

1. Find your water system’s name. It is on your water bill. If you are not sure, our ZIP code water check shows the system that serves your ZIP, its water source and its latest lead results from EPA records.
2. Open the Data Finder and choose your state. Then type the system name, or its ID (the PWSID, which starts with your state’s two letters).
3. Filter to PFOA and PFOS first. These are the two with federal limits that the EPA has proposed to keep. Then look at PFHxS, PFNA, HFPO-DA (GenX) and PFBS.
4. Look at every sample, not just one. Larger systems often have several wells or treatment plants, and each entry point was sampled separately. Your home may get water from one or a blend.
5. Write down the highest and the typical numbers in ppt, and the sample dates.

The EPA notes that UCMR 5 reporting levels are based on what labs can reliably measure, not on health effects. A result of “ND” or “<MRL” means below that reporting level, not zero. For PFOA and PFOS the level was 4 ppt (0.004 micrograms per liter).

For people comfortable with spreadsheets, the EPA’s downloadable UCMR 5 data files also include the ZIP codes each system reported serving. That is how many “PFAS by ZIP code” maps are built. Third-party maps, such as the Environmental Working Group’s tap water database, can be handy, but they may compare results with their own health guidelines rather than the EPA limits, so read the fine print.

Step 2: Read your water quality report

Every community water system must send customers an annual water quality report, also called a Consumer Confidence Report (CCR), usually by July 1. Many utilities already list their PFAS sampling in it, sometimes in a separate “unregulated contaminants” table.

Under the EPA’s 2024 PFAS rule, systems must finish initial PFAS monitoring by 2027 and start giving customers information on PFAS levels beginning in 2027. So reports issued from 2027 onward should include PFAS more consistently. Our guide to choosing a water filter explains how to turn a report into a filter decision.

When you read the table, look for the contaminant name, the unit (ppt or ng/L are the same thing), the average and the range. If PFAS is not mentioned at all, it does not mean there is none. Move on to Step 3.

Step 3: Ask your utility or state

Utilities answer this question often. Call or email customer service and ask three things: the most recent PFOA and PFOS results in ppt, which source or treatment plant serves your address, and whether any treatment for PFAS is planned. Many larger utilities also post a PFAS page with sample results.

State environment and health agencies are another source. Several states sampled for PFAS before the federal rule and publish the data, and some set their own PFAS standards. Search for your state’s name plus “PFAS drinking water” to find the official page.

Private well? Test it yourself

The EPA does not regulate private wells, and no utility tests them. The USGS study found PFAS levels in private wells similar to public supplies, so if you live near a known source, such as an airport, military base, fire training site, landfill or factory that used PFAS, a test is worth considering.

• Use a state-certified or accredited lab. Your state health or environment department can name labs that test drinking water for PFAS.
• Ask for EPA Method 533 or 537.1. These are the EPA’s drinking water methods. Penn State Extension notes that Method 537.1 measures 18 PFAS and Method 533 measures 25.
• Follow the lab’s sampling kit exactly. PFAS are in many everyday products, so labs give specific instructions to avoid contaminating the sample.
• Expect a real cost. Penn State Extension put PFAS testing at around $250 to $500 per sample in its July 2024 update. Ask your state whether free or subsidized testing is offered near known sites.

Store-bought “PFAS test strips” or general water test kits are not a substitute for a certified lab result at the parts-per-trillion level the EPA limits use.

How to read a PFAS result

PFAS are measured in tiny amounts. One part per trillion is one nanogram per liter. Results may be shown as ppt, ng/L or micrograms per liter (µg/L), where 0.004 µg/L equals 4 ppt.

PFAS	EPA limit set in 2024	Status as of October 6, 2026
PFOA	4.0 ppt	Proposed to keep; compliance deadline proposed to move from 2029 to 2031 for eligible systems
PFOS	4.0 ppt	Proposed to keep; same deadline proposal
PFHxS	10 ppt	Proposed to rescind (May 2026)
PFNA	10 ppt	Proposed to rescind (May 2026)
HFPO-DA (GenX)	10 ppt	Proposed to rescind (May 2026)
Mixture of PFHxS, PFNA, GenX and PFBS	Hazard Index of 1	Proposed to rescind (May 2026)

Three points make results easier to read. First, utility compliance is based on a running annual average, so one high sample is a warning sign, not a violation. Second, the limit is per chemical for PFOA and PFOS, so a result of 3 ppt PFOA and 3 ppt PFOS is below both limits. Third, “ND” means below the reporting level, which is not the same as zero. If you want PFAS as low as practical, a certified filter can take you below what the utility is required to reach.

What the EPA rule says now

The EPA finalized the first national PFAS drinking water rule on April 10, 2024. It set limits of 4 ppt each for PFOA and PFOS, 10 ppt each for PFHxS, PFNA and HFPO-DA, and a combined Hazard Index for mixtures. Systems were given until 2027 to finish initial monitoring and until 2029 to meet the limits.

On May 18, 2026, the EPA proposed two changes. One would keep the PFOA and PFOS limits but let eligible systems take until April 2031 to comply, with a duty to tell customers about any extension. The other would rescind the limits for PFHxS, PFNA, HFPO-DA and the mixture. The comment period closed on July 20, 2026. As of October 6, 2026, these were proposals, not final rules, so check the EPA’s PFAS page for the current status.

For your household, the practical message has not changed: PFOA and PFOS at 4 ppt remain the federal yardstick, and you can compare your utility’s numbers with them today.

What PFAS exposure is linked to

The CDC’s Agency for Toxic Substances and Disease Registry (ATSDR) lists health effects that studies have linked to certain PFAS, including higher cholesterol levels, a lower antibody response to some vaccines, changes in liver enzymes, small decreases in birth weight, pregnancy-induced high blood pressure and preeclampsia, and kidney and testicular cancer (for PFOA). Scientists are still learning about the effects of mixtures of PFAS.

There is no set of symptoms that tells you PFAS are in your water. The only way to know is a test result. If you have questions about your own health or about PFAS blood testing, talk to your doctor; ATSDR also publishes guidance on PFAS blood tests for clinicians and the public. This page is not medical advice.

If your water has PFAS: what to do

If your results are above 4 ppt for PFOA or PFOS, or you simply want lower levels, a home filter is the practical step while utilities work on treatment. The EPA’s advice is to look for a filter certified to NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction, and to replace cartridges and membranes on the maker’s schedule. Certification can come from NSF, CSA Group, IAPMO R&T, UL or WQA.

On the listing, look for “PFOA/PFOS reduction” or “total PFAS reduction.” The total PFAS claim also covers PFHpA, PFHxS, PFNA and PFBS. Our guide to NSF 53 vs 58 explains both claims, and how to check if a filter is really NSF certified shows how to confirm a model in a few minutes.

Independent research supports the order of those cards. A 2020 Duke University and NC State study found that under-sink reverse osmosis and two-stage filters removed 94% or more of the PFAS measured, while activated carbon filters removed 73% on average with wide variation. The EPA says reverse osmosis membranes are typically more than 90% effective across a wide range of PFAS. See what reverse osmosis removes for the full picture.

Already own a filter? Check it before buying anything. Many popular pitchers and refrigerator cartridges have no PFAS claim. Our guides to what Brita removes and whether fridge filters remove PFAS cover the common cases. Boiling is not a fix: see does boiling water remove PFAS. Not sure where to start? The 15-second filter finder suggests a filter type for your situation.

Sources and how we checked this page

Facts on this page come from the EPA, the USGS, ATSDR (CDC), Penn State Extension, trade reporting on EPA data and peer-reviewed research, checked on October 6, 2026. We do not test water or filters in a lab.

• EPA: Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) Data Finder
• EPA: UCMR 5 fact sheet, reporting levels and methods (PDF)
• EPA: Per- and polyfluoroalkyl substances (PFAS) drinking water regulation
• EPA: Proposed PFOA and PFOS compliance extension rule
• Federal Register: Rescission of regulatory determinations for four PFAS (May 20, 2026)
• Waste Dive: EPA to formally rescind certain PFAS drinking water regulations (May 19, 2026)
• Water Online: EPA releases final UCMR drinking water data for PFAS and lithium (2026)
• Pace Analytical: Making sense of UCMR 5 results (April 2026)
• NGWA: USGS report estimates PFAS in 45 percent of US tap water (2023)
• ATSDR: PFAS health effects
• Penn State Extension: PFAS drinking water standards, testing and treatment
• EPA: Identifying drinking water filters certified to reduce PFAS
• EPA: Reducing PFAS in your drinking water with a home filter (fact sheet, PDF)
• Duke University study coverage: Not all home drinking water filters completely remove PFAS (2020)
• EPA: Private drinking water wells