Interactive PFAS Contamination Map
Explore PFAS "forever chemical" contamination across all 50 US states. Based on EPA UCMR3 and UCMR5 drinking water testing data covering 10,612 public water systems.
Quick Answers
What does this PFAS map show? Every US public water system tested under EPA UCMR3 (2013-2015) and UCMR5 (2023-2025). Click any state to see city-by-city PFAS detection rates, average and maximum levels, and affected populations.
How many Americans are affected? An estimated 110M+ Americans are served by water systems with detectable PFAS. 4,397 of 10,612 tested systems (41.4%) have at least one PFAS compound above EPA reporting thresholds.
What is the worst-contaminated state? Northern Mariana Islands has the highest recorded PFAS level at 7,000 ppt. See the full ranked table below.
What is the EPA PFAS limit? The EPA finalized enforceable limits in 2024: 4 parts per trillion (ppt) for PFOA and PFOS individually. Utilities must comply by 2029. Independent health guidelines (EWG, C8 Study Panel) recommend levels 1,000x lower.
National PFAS Contamination at a Glance
- Systems Tested: 10,612
- Systems with PFAS Detected: 4,397 (41.4%)
- Average Level When Detected: 0.4 ppt
- Worst Contamination: 7,000 ppt (Northern Mariana Islands)
- Estimated Americans Affected: 110M+
The EPA's enforceable PFAS limit is 4 ppt for PFOA and PFOS. Independent health guidelines recommend levels 1,000x lower. Check your water by ZIP code at knowyourexposure.com.
Most Contaminated States by PFAS Levels
Ranked by average PFAS level when detected. Click any state to see city-by-city data.
| Rank | State | Avg ppt | Max ppt | Systems | Detection Rate |
|---|---|---|---|---|---|
| 1 | Northern Mariana Islands | 11.4 | 7000 | 2 | 50% |
| 2 | Arizona | 2.1 | 796 | 158 | 50% |
| 3 | Navajo Nation | 1.7 | 230 | 13 | 54% |
| 4 | New Mexico | 1.6 | 537 | 72 | 50% |
| 5 | South Dakota | 1.5 | 440 | 51 | 51% |
| 6 | Iowa | 1.2 | 480 | 161 | 50% |
| 7 | North Dakota | 1.2 | 0 | 41 | 51% |
| 8 | Kansas | 0.9 | 204 | 111 | 50% |
| 9 | Nebraska | 0.9 | 0 | 57 | 51% |
| 10 | Nevada | 0.8 | 248 | 60 | 50% |
| 11 | Texas | 0.7 | 403 | 1,176 | 50% |
| 12 | Idaho | 0.6 | 150 | 64 | 50% |
| 13 | Colorado | 0.5 | 1300 | 185 | 50% |
| 14 | Missouri | 0.5 | 222 | 238 | 50% |
| 15 | Mississippi | 0.5 | 280 | 236 | 50% |
| 16 | Montana | 0.5 | 0 | 47 | 51% |
| 17 | Utah | 0.5 | 960 | 131 | 50% |
| 18 | Connecticut | 0.4 | 231 | 119 | 50% |
| 19 | Louisiana | 0.4 | 0 | 259 | 50% |
| 20 | Wyoming | 0.4 | 0 | 35 | 51% |
What This Data Means
PFAS (per- and polyfluoroalkyl substances), also called "forever chemicals," accumulate in the body and have been linked to cancer, thyroid disease, immune suppression, and developmental harm. The EPA's UCMR5 program tested water systems nationwide between 2023 and 2025, revealing widespread contamination from industrial sources, military firefighting foam (AFFF), and consumer products.
To see contamination data specific to your water supply, enter your ZIP code on the KnowYourExposure homepage. For a full compound-by-compound breakdown of your water, including filter recommendations and trend analysis, get the $9.99 comprehensive report.