PFAS Contamination Maps: How to Check If PFAS Is in Your Water (Zip Code Lookups and Why They Mislead)

You saw the map. Maybe it was a screenshot in a news story, maybe someone posted it in the neighborhood group — a spread of orange dots, one of them uncomfortably close to your town. So now you're zoomed all the way in, trying to work out whether that dot means your tap, your kids' bath water, the well behind the house near the base. The map won't tell you. None of them will, and that's not because your worry is overblown — the U.S. Geological Survey estimates at least 45% of U.S. tap water contains one or more PFAS compounds, so this is a real problem with real science behind it. The trouble is that every public dashboard answers a regionalquestion, while the question keeping you up is about one tap. This guide walks through each major map, what it shows and what it hides, why zip-code lookups give misleading answers, and how to get from "my area is orange on a map" to "here's what the records say about my water system."

The major PFAS maps, compared

Four public maps cover nearly everything worth knowing. They don't agree with each other, and they were never supposed to — each was built for a different job:

1. EWG PFAS Contamination Map (ewg.org) — the one most people land on, and probably the one you were squinting at. The Environmental Working Group plots thousands of sites with known PFAS detections: public water systems, military installations, and industrial sources. It's broad and easy to browse. The catch is what a dot actually means: a detection happened somewhere in that system or at that site. It doesn't tell you whether the contamination reaches a given tap, at what level, or whether treatment has since been installed.
2. EPA PFAS Analytic Tools (echo.epa.gov) — the most complete federal view. It layers drinking-water testing results, industrial dischargers, Superfund sites, and spill records on one map. It's the closest thing to a master PFAS map, but it assumes you already know your water system's name and ID, and the interface was built for regulators, not homebuyers.
3. EPA UCMR 5 results (epa.gov/dwucmr) — not a map at all, but the underlying dataset most maps draw from: 2023–2025 testing of public water systems for 29 PFAS compounds. If your utility serves 3,300+ people, its results are in here, compound by compound.
4. USGS tap-water study (usgs.gov) — the source of the "45% of U.S. tap water" statistic. USGS sampled taps directly, including private wells that no regulatory dataset covers. Great for national context. Useless for looking up a specific location, though — it sampled a few hundred sites, and yours almost certainly wasn't one of them.

PFAS in water by zip code: why the lookup misleads

The most common search is some version of "PFAS in water by zip code." It feels like the right question — it's how you look up everything else about a place. But zip codes are postal-delivery geography, drawn for mail trucks. PFAS contamination follows two completely different shapes:

• Water-system shape. Your exposure through tap water depends on which public water system serves your address and which source wells or intakes it draws from. Utility service areas routinely cross zip-code lines, and a single zip code can contain three or four systems with very different test results. A zip-level summary averages them into mush.
• Site-radius shape. Contamination from a source — a military base that used firefighting foam, an industrial discharger, a Superfund site — spreads as a plume governed by groundwater flow. Distance and direction from the site matter; the zip code boundary does not. A home two miles downgradient of a source can be at meaningfully higher risk than a home in the same zip code five miles upgradient.

This is why two neighbors who compare notes after a zip-code lookup can both be wrong, in opposite directions. One walks away falsely reassured because the zip average looks clean; the other spends a sleepless week over a detection in a system that doesn't even serve their street. The honest unit of analysis is the address — geocode it, identify the serving water system, pull that system's results, and measure distances to known PFAS sources.

PFAS testing: water tests vs. blood tests

Once a map (or a report) tells you PFAS is plausible at your location, testing is the natural next question — and there are two very different tests that people conflate.

A water test for PFASmeasures what's coming out of your tap right now. There's no credible instant test strip at the part-per-trillion concentrations that matter; real testing means a certified lab running EPA Method 533 or 537.1 on a sample you collect. Mail-in PFAS water test kits from EPA-certified labs typically run about $250–$400. That price is exactly why the order of operations matters: check the free public records for your water system first. If your utility already reported UCMR 5 results, you may get your answer for nothing — or learn precisely which compounds to pay a lab to look for. One big exception: if you're on a private well, especially anywhere near a base or airfield that used firefighting foam, skip straight to lab testing. No public dataset is monitoring your well for you, and nobody will send you a notice if something's in it.

A PFAS blood testmeasures what has accumulated in your body over years of exposure from all sources — water, food, consumer products. The National Academies' 2022 guidance (summarized by ATSDR) recommends clinical follow-up tiers starting at 2 ng/mL. If you've lived near a known source for years, it's a reasonable conversation to have with your doctor. But it can't tell you whether your water is the problem — the exposure could just as easily have come from food packaging or an old job — so treat it as a complement to water testing, not a substitute.

Do water filters certified to remove PFAS actually work?

Yes — and if you're lying awake over this, here's the genuinely good news: home treatment works, with two big caveats — certification and maintenance. The certifications to look for are NSF/ANSI 53 (activated carbon filters with an explicit PFOA/PFOS reduction claim) and NSF/ANSI 58(reverse osmosis). Independent testing, including a widely cited Duke University and NC State study of home filters, found that properly maintained reverse osmosis and two-stage systems removed PFAS at well over 90%, while uncertified pitcher and fridge filters were inconsistent — some barely reduced PFAS at all, and a saturated carbon filter can even release contaminants back into the water. So: does reverse osmosis remove PFAS? Yes, it's the most reliable home option. Does the random pitcher in your fridge? Not unless its packaging cites NSF/ANSI 53 with a PFAS claim — and not after you've ignored the cartridge replacement schedule.

Checking a specific city

If you want a faster starting point than the federal dashboards, we aggregate the same EPA records into city-level pages — see the Water & PFAS by City directory. A few examples of how different the picture looks city to city:

• San Antonio, TX — multiple military installations with documented AFFF use ring the city, making distance-to-source the key variable.
• Wilmington, NC — GenX contamination of the Cape Fear River from the Chemours facility upstream.
• Grand Rapids, MI — the Wolverine Worldwide tannery-waste cluster, one of the country's best-documented PFAS plumes.

One more thing to hold onto while reading any of this: EPA's 2024 drinking-water standards (4 ppt for PFOA and PFOS) don't require utility compliance until 2029. Until then, "legal" and "below the new limits" are not the same thing. Your water can exceed the new limits today and nobody is obligated to fix it yet — which is why looking at the actual reported numbers beats trusting that no news is good news.

A sane order of operations

If you take nothing else from this page, take the sequence. It keeps you from paying for a lab test you didn't need — and from skipping the one you did.

1. Browse a map (EWG or EPA's PFAS Analytic Tools) for regional context.
2. Identify the water system serving the specific address — not the zip code — and pull its UCMR 5 / violation records, or let an address-level report do the joins for you.
3. If records show detections, you're near a known source, or you're on a private well: order a certified PFAS water test ($250–$400).
4. If results warrant it: install an NSF/ANSI 53- or 58-certified filter, and discuss blood testing with a clinician if long-term exposure looks likely.

Related reading: how to check PFAS near a specific address, the PFAS homebuyer guide, PFAS from military bases, and checking drinking water quality records.