What EPA found in your tap water
Between 2023 and 2025, EPA had 10,313 public water systems tested for 29 PFAS. The final results came out in August 2026. Enter your ZIP code to see your utility's numbers against the federal limits.
35% of systems had at least one PFAS detected.
1,165 systems averaged above an EPA limit at a sampling point, serving about 55 million people.
1,144 of those were over on PFOA or PFOS, the two limits EPA proposed keeping in May 2026.
The largest systems above a limit
Ranked by people served. Values are averages at the system's worst sampling point, in parts per trillion.
| Water system | State | People | PFOA | PFOS | Over |
|---|---|---|---|---|---|
| Mdwasa - Main System | FL | 2,377,460 | 12.3 | 31.4 | PFOA, PFOS, HI |
| Philadelphia Water Department | PA | 1,600,000 | 7.3 | 5.0 | PFOA, PFOS |
| Fairfax County Water Authority | VA | 1,121,613 | 4.6 | 2.6 | PFOA |
| Suffolk County Water Authority | NY | 1,100,000 | 6.0 | 12.1 | PFOA, PFOS, HI |
| Metropolitano | PR | 1,084,637 | 2.7 | 6.2 | PFOS |
| City of Fort Worth | TX | 955,900 | 5.9 | 6.2 | PFOA, PFOS, PFHxS, HI |
| Aqua Pa Main System | PA | 822,600 | 11.8 | 8.9 | PFOA, PFOS, HI |
| Suez Water New Jersey Hackensack | NJ | 792,713 | 13.0 | 6.3 | PFOA, PFOS |
| Cincinnati Public Water System | OH | 750,200 | 0.0 | 5.2 | PFOS |
| El Paso Water Utilities Public Service B | TX | 747,168 | 0.0 | 6.4 | PFOS |
| City of Tampa Water Department | FL | 733,886 | 2.2 | 5.7 | PFOS |
| Palm Beach County Water Utilities | FL | 671,114 | 8.2 | 19.0 | PFOA, PFOS |
| Nj American Water - Raritan | NJ | 615,430 | 6.6 | 6.0 | PFOA, PFOS |
| City of Fresno | CA | 545,716 | 13.5 | 21.5 | PFOA, PFOS, PFHxS, HI |
| City of Sacramento Main | CA | 527,979 | 16.4 | 38.8 | PFOA, PFOS, PFHxS, HI |
| Hcpud/south-central | FL | 515,012 | 0.0 | 4.6 | PFOS |
| Truckee Meadows Water Authority | NV | 442,000 | 5.2 | 13.0 | PFOA, PFOS, PFHxS, HI |
| Salt Lake City Water System | UT | 383,612 | 0.0 | 7.1 | PFOS, PFHxS, HI |
| Nj American Water - Coastal North | NJ | 377,613 | 7.2 | 0.0 | PFOA |
| City of Vancouver | WA | 373,047 | 10.9 | 18.4 | PFOA, PFOS |
Which PFAS showed up most
Short-chain PFAS were the most common finds. Most have no federal limit, and carbon filters remove them less reliably than PFOA and PFOS, which matters when choosing a filter.
| PFAS | Systems where detected |
|---|---|
| PFPeA Perfluoropentanoic acid | 2,066 |
| PFBA Perfluorobutanoic acid | 1,935 |
| PFHxA Perfluorohexanoic acid | 1,807 |
| PFBS Perfluorobutanesulfonic acid | 1,707 |
| PFOS Perfluorooctanesulfonic acid | 1,352 |
| PFOA Perfluorooctanoic acid | 1,305 |
| PFHxS Perfluorohexanesulfonic acid | 1,037 |
| PFHpA Perfluoroheptanoic acid | 555 |
| 6:2 FTS 6:2 fluorotelomer sulfonic acid | 183 |
| PFNA Perfluorononanoic acid | 83 |
The limits, and where they stand
EPA's April 2024 rule set enforceable limits of 4 ppt for PFOA and for PFOS, 10 ppt each for PFHxS, PFNA and HFPO-DA (GenX), and a hazard index of 1 for mixtures of PFHxS, PFNA, GenX and PFBS. Water systems have until 2029 to comply.
On May 18, 2026, EPA proposed rescinding the four non-PFOA/PFOS limits and giving utilities until 2031 for PFOA and PFOS. The comment period closed July 20, 2026. Until a final rule is published the 2024 limits stay in force, so we show all of them and label which ones are proposed for removal.
How we built this
We downloaded EPA's final UCMR 5 occurrence file (published August 2026) and grouped every result by water system. For each PFAS we report how many samples detected it, the single highest result, and the average of all results at each sampling point, taking the worst point. Results below EPA's minimum reporting level count as zero, which is how running annual averages are calculated for compliance. Hazard index is computed per sampling event from the four PFAS in the mixture limit.
Our figure for large systems (serving over 10,000 people) averaging above a limit is 15.4%. EPA's own July 2026 data summary puts it at 15.5%, the gap coming from EPA using only complete sample sets. Population served comes from EPA's SDWIS database. ZIP codes are the ones each utility reported to EPA, so a ZIP can list more than one system.
These are not compliance results, and they reflect water as it left the treatment plant or entered the distribution system, not your tap. The raw data is public: EPA UCMR occurrence data. Journalists and researchers are welcome to use our summaries with a link back.
Use this data
Free to reuse with a link to this page. Download the CSV (10,313 systems: worst sampling point averages and maximums for the regulated PFAS, detection lists, population served, and a link to each system's page).
Newsrooms can embed the ZIP lookup:
<iframe src="https://wellandtap.com/embed/pfas/" title="PFAS lookup by ZIP code" width="100%" height="720" style="border:0" loading="lazy"></iframe>
<p>Data: <a href="https://wellandtap.com/pfas/">Well & Tap PFAS lookup</a>, from EPA UCMR 5.</p>Common questions
What is a safe level of PFAS in drinking water?
EPA considers there to be no safe level of PFOA or PFOS, which is why its health goal for both is zero. The enforceable limit, set at 4 parts per trillion, is the lowest level that can be reliably measured and treated.
My utility is above the limit. Is it breaking the law?
Not yet. Utilities have until 2029 to meet the 2024 limits, and EPA proposed in May 2026 to extend the PFOA and PFOS deadline to 2031. UCMR 5 results are also not compliance samples. They show where treatment will likely be needed.
Does boiling water remove PFAS?
No. Boiling concentrates PFAS slightly as water evaporates. Reverse osmosis, activated carbon with enough contact time, and ion exchange resin are the treatments that work.
Why is my ZIP code missing?
EPA tested every system serving more than 3,300 people and a sample of smaller ones. Very small systems and all private wells are not in the data.