Well water by state

Every state has a page, and every county in it. Counties with state or federal test results show measured shares; the rest carry the USGS national estimate until results are published.

• Alabama67 counties539,394 people on wells
• Alaska13 counties
• Arizona15 counties218,170 people on wells
• Arkansas75 counties144,444 people on wells
• California58 counties1,435,510 people on wells
• Colorado63 counties286,474 people on wells
• Connecticut9 counties
• Delaware3 counties181,640 people on wells
• Florida67 counties2,460,295 people on wells
• Georgia157 counties1,514,397 people on wells
• Hawaii4 counties56,296 people on wells
• Idaho44 counties396,215 people on wells
• Illinois102 counties1,151,113 people on wells
• Indiana92 counties1,677,339 people on wells
• Iowa99 counties494,022 people on wells
• Kansas103 counties149,282 people on wells
• Kentucky120 counties440,663 people on wells
• Louisiana64 counties491,582 people on wells
• Maine16 counties660,497 people on wells
• Maryland24 counties1,423,948 people on wells
• Massachusetts13 counties615,948 people on wells
• Michigan83 counties2,597,314 people on wells
• Minnesota87 counties1,176,917 people on wells
• Mississippi82 counties434,766 people on wells
• Missouri107 counties821,343 people on wells
• Montana56 counties304,630 people on wells
• Nebraska93 counties171,440 people on wells
• Nevada17 counties192,557 people on wells
• New Hampshire10 counties333,393 people on wells
• New Jersey20 counties966,024 people on wells
• New Mexico33 counties292,165 people on wells
• New York61 counties2,499,435 people on wells
• North Carolina100 counties2,407,661 people on wells
• North Dakota53 counties46,353 people on wells
• Ohio86 counties1,861,023 people on wells
• Oklahoma77 counties356,860 people on wells
• Oregon36 counties631,538 people on wells
• Pennsylvania67 counties3,470,761 people on wells
• Rhode Island5 counties112,853 people on wells
• South Carolina46 counties1,182,721 people on wells
• South Dakota65 counties121,341 people on wells
• Tennessee95 counties594,482 people on wells
• Texas254 counties1,315,073 people on wells
• Utah29 counties61,378 people on wells
• Vermont14 counties243,796 people on wells
• Virginia116 counties1,558,115 people on wells
• Washington39 counties1,023,853 people on wells
• West Virginia55 counties391,591 people on wells
• Wisconsin72 counties1,598,065 people on wells
• Wyoming23 counties119,066 people on wells