EPA data as of Oct 2026 · page updated 2026-10-29

Drinking water & radon by state

Pick a state for its radon map, the water systems with the most violations, the highest lead and PFAS results, and every ZIP code. Hover or tap a state to preview it.

Share of ZIP codes in EPA radon zone 10% → 100%

Small states:CT DE DC MA NH NJ RI VT

Alabama804 ZIPs Alaska272 ZIPs Arizona522 ZIPs Arkansas693 ZIPs California2,554 ZIPs Colorado625 ZIPs Connecticut418 ZIPs Delaware93 ZIPs District of Columbia271 ZIPs Florida1,454 ZIPs Georgia937 ZIPs Hawaii131 ZIPs Idaho312 ZIPs Illinois1,545 ZIPs Indiana929 ZIPs Iowa1,042 ZIPs Kansas741 ZIPs Kentucky933 ZIPs Louisiana710 ZIPs Maine478 ZIPs Maryland599 ZIPs Massachusetts675 ZIPs Michigan1,154 ZIPs Minnesota943 ZIPs Mississippi524 ZIPs Missouri1,145 ZIPs Montana399 ZIPs Nebraska609 ZIPs Nevada250 ZIPs New Hampshire280 ZIPs New Jersey715 ZIPs New Mexico419 ZIPs New York2,126 ZIPs North Carolina1,072 ZIPs North Dakota405 ZIPs Ohio1,391 ZIPs Oklahoma760 ZIPs Oregon473 ZIPs Pennsylvania2,108 ZIPs Puerto Rico176 ZIPs Rhode Island88 ZIPs South Carolina526 ZIPs South Dakota382 ZIPs Tennessee774 ZIPs Texas2,572 ZIPs Utah337 ZIPs Vermont305 ZIPs Virginia1,197 ZIPs Washington708 ZIPs West Virginia843 ZIPs Wisconsin872 ZIPs Wyoming192 ZIPs

What this is — and isn’t. These are records your water utility and state reported to the EPA, and the EPA’s radon map for your county. They describe the system and the area, not the water from your own tap or the air in your home. For that, read your utility’s annual Consumer Confidence Report and test: lead and radon tests are inexpensive.