Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Gray | Texas | 10 | 21,519 | 920 |
| White | Indiana | 78 | 21,504 | 9,498 |
| Austin | Texas | 32 | 21,500 | 1,723 |
| Vernon | Missouri | 8 | 21,484 | 945 |
| Newton | Mississippi | 11 | 21,475 | 3,819 |
| Vance | North Carolina | 35 | 21,462 | 7,525 |
| Coshocton | Ohio | 35 | 21,460 | 2,973 |
| Murray | Oklahoma | 9 | 21,453 | 1,178 |
| Rockcastle | Kentucky | 5 | 21,448 | 599 |
| Clark | Arkansas | 12 | 21,445 | 359 |
| Saline | Missouri | 11 | 21,402 | 911 |
| Crenshaw | Alabama | 7 | 21,390 | 378 |
| McDuffie | Georgia | 4 | 21,387 | 221 |
| Assumption Parish | Louisiana | 1 | 21,366 | 208 |
| Holmes | Mississippi | 21 | 21,350 | 8,936 |
| Barranquitas Municipio | Puerto Rico | 12 | 21,283 | 3,701 |
| Macon | Missouri | 7 | 21,230 | 306 |
| Bee | Texas | 8 | 21,196 | 1,188 |
| Barceloneta Municipio | Puerto Rico | 7 | 21,188 | 566 |
| Union | Oregon | 23 | 21,181 | 1,293 |
| Wells | Indiana | 25 | 21,120 | 1,203 |
| Hardin | Ohio | 31 | 21,114 | 2,070 |
| Pamlico | North Carolina | 3 | 21,081 | 276 |
| Conway | Arkansas | 5 | 21,073 | 133 |
| Lyon | Minnesota | 16 | 21,039 | 218 |
| Lawrence | Arkansas | 11 | 21,024 | 500 |
| Sullivan | Indiana | 13 | 21,006 | 781 |
| Wayne | Kentucky | 1 | 21,000 | 68 |
| Toombs | Georgia | 18 | 20,993 | 2,252 |
| Fluvanna | Virginia | 22 | 20,992 | 737 |
| West Feliciana Parish | Louisiana | 4 | 20,986 | 125 |
| Wayne | Mississippi | 7 | 20,868 | 5,876 |
| Trigg | Kentucky | 11 | 20,836 | 992 |
| Arenac | Michigan | 68 | 20,827 | 2,121 |
| Morovis Municipio | Puerto Rico | 2 | 20,826 | 584 |
| Weakley | Tennessee | 11 | 20,796 | 305 |
| Uinta | Wyoming | 13 | 20,786 | 338 |
| Crawford | Illinois | 9 | 20,783 | 161 |
| County NN005 | Navajo Nation | 22 | 20,758 | 1,970 |
| Bosque | Texas | 32 | 20,757 | 1,370 |
| Cabo Rojo Municipio | Puerto Rico | 1 | 20,749 | 452 |
| Orange | Vermont | 70 | 20,735 | 8,039 |
| Towns | Georgia | 10 | 20,710 | 349 |
| Franklin | Florida | 11 | 20,659 | 1,255 |
| Mille Lacs | Minnesota | 93 | 20,627 | 566 |
| Beckham | Oklahoma | 9 | 20,527 | 1,670 |
| Falls | Texas | 12 | 20,515 | 2,287 |
| Kent | Maryland | 58 | 20,499 | 1,297 |
| Washington | Illinois | 13 | 20,496 | 276 |
| Oconto | Wisconsin | 203 | 20,416 | 3,478 |
| Moore | Texas | 13 | 20,414 | 456 |
| Ashley | Arkansas | 11 | 20,384 | 690 |
| Eastland | Texas | 13 | 20,303 | 2,796 |
| Winston | Mississippi | 11 | 20,299 | 3,162 |
| Schoharie | New York | 67 | 20,230 | 3,711 |
| Warren | Missouri | 27 | 20,212 | 1,083 |
| Nodaway | Missouri | 12 | 20,189 | 782 |
| Hertford | North Carolina | 8 | 20,174 | 761 |
| Cibola | New Mexico | 18 | 20,138 | 3,798 |
| Reeves | Texas | 21 | 20,117 | 2,125 |
| Lawrence | Missouri | 36 | 20,101 | 4,797 |
| Carroll | Tennessee | 11 | 20,076 | 651 |
| New Kent | Virginia | 37 | 20,054 | 1,517 |
| Claiborne Parish | Louisiana | 12 | 20,051 | 848 |
| Webster | Missouri | 29 | 20,029 | 2,150 |
| Waldo | Maine | 77 | 19,984 | 5,716 |
| Jefferson | Kansas | 18 | 19,964 | 1,089 |
| Fayette | Texas | 13 | 19,961 | 1,413 |
| Buchanan | Virginia | 6 | 19,949 | 200 |
| Davison | South Dakota | 4 | 19,917 | 178 |
| Trempealeau | Wisconsin | 75 | 19,857 | 2,859 |
| Van Wert | Ohio | 31 | 19,849 | 2,375 |
| Caroline | Maryland | 64 | 19,836 | 2,080 |
| Chickasaw | Mississippi | 12 | 19,833 | 7,527 |
| Union | Tennessee | 9 | 19,831 | 681 |
| Payette | Idaho | 20 | 19,821 | 2,033 |
| Lake | Montana | 91 | 19,815 | 7,834 |
| Fayette | Alabama | 5 | 19,809 | 125 |
| Ogemaw | Michigan | 118 | 19,809 | 706 |
| Carroll | Iowa | 13 | 19,807 | 1,060 |
| Grundy | Tennessee | 5 | 19,807 | 287 |
| Walthall | Mississippi | 6 | 19,772 | 1,466 |
| Yates | New York | 68 | 19,749 | 4,519 |
| Jackson | Wisconsin | 102 | 19,736 | 2,821 |
| Aransas | Texas | 18 | 19,735 | 573 |
| County 06035 | 06 | 10 | 19,730 | 796 |
| Decatur | Georgia | 24 | 19,689 | 1,001 |
| Manistee | Michigan | 95 | 19,677 | 2,236 |
| Sumter | Alabama | 4 | 19,668 | 309 |
| Whitley | Indiana | 40 | 19,660 | 2,758 |
| Franklin | Georgia | 9 | 19,643 | 679 |
| Labette | Kansas | 15 | 19,599 | 1,630 |
| Hancock | West Virginia | 9 | 19,588 | 1,607 |
| Jefferson | Idaho | 63 | 19,584 | 2,465 |
| St. Francis | Arkansas | 9 | 19,582 | 210 |
| Alpena | Michigan | 49 | 19,573 | 1,613 |
| Socorro | New Mexico | 18 | 19,560 | 2,053 |
| County 09031 | 09 | 23 | 19,530 | 2,193 |
| McIntosh | Oklahoma | 13 | 19,522 | 5,329 |
| Luna | New Mexico | 14 | 19,514 | 1,440 |