Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Lee | Texas | 7 | 26,350 | 1,200 |
| Miami | Indiana | 66 | 26,268 | 10,453 |
| County NN017 | Navajo Nation | 27 | 26,234 | 4,391 |
| Concordia Parish | Louisiana | 8 | 26,222 | 3,813 |
| Jasper | Iowa | 11 | 26,205 | 526 |
| Dunn | Wisconsin | 85 | 26,162 | 3,619 |
| Hickman | Tennessee | 10 | 26,152 | 640 |
| Ellis | Kansas | 14 | 26,113 | 2,063 |
| Grant Parish | Louisiana | 13 | 26,060 | 2,043 |
| Marengo | Alabama | 7 | 25,983 | 343 |
| County NN045 | Navajo Nation | 19 | 25,958 | 2,250 |
| Henry | Tennessee | 20 | 25,949 | 463 |
| Iowa | Wisconsin | 77 | 25,946 | 2,450 |
| Montgomery | Illinois | 24 | 25,934 | 1,355 |
| LaGrange | Indiana | 210 | 25,912 | 12,821 |
| Adair | Missouri | 4 | 25,904 | 169 |
| Jim Wells | Texas | 13 | 25,890 | 7,346 |
| Boone | Arkansas | 17 | 25,879 | 688 |
| Jennings | Indiana | 10 | 25,878 | 2,231 |
| Greene | Georgia | 29 | 25,860 | 1,398 |
| Franklin Parish | Louisiana | 7 | 25,752 | 338 |
| Utuado Municipio | Puerto Rico | 16 | 25,734 | 11,062 |
| Randolph | West Virginia | 29 | 25,710 | 6,462 |
| Limestone | Texas | 23 | 25,697 | 6,170 |
| Benzie | Michigan | 113 | 25,693 | 1,325 |
| Wasco | Oregon | 44 | 25,689 | 4,505 |
| Bandera | Texas | 71 | 25,683 | 4,904 |
| Adams | Washington | 48 | 25,650 | 3,951 |
| Saline | Illinois | 15 | 25,649 | 484 |
| Lawrence | South Dakota | 73 | 25,648 | 6,945 |
| Mariposa | California | 69 | 25,617 | 887 |
| Sanilac | Michigan | 77 | 25,615 | 2,021 |
| Orocovis Municipio | Puerto Rico | 18 | 25,604 | 8,262 |
| Marion | Missouri | 3 | 25,603 | 196 |
| Dorchester | Maryland | 75 | 25,599 | 1,468 |
| Clinton | Missouri | 7 | 25,585 | 194 |
| Cass | Indiana | 42 | 25,534 | 3,301 |
| Carroll | Arkansas | 48 | 25,496 | 2,096 |
| Daviess | Indiana | 8 | 25,462 | 720 |
| Smyth | Virginia | 20 | 25,446 | 756 |
| Colfax | New Mexico | 52 | 25,433 | 5,082 |
| Fayette | Ohio | 14 | 25,430 | 835 |
| Delaware | Oklahoma | 37 | 25,428 | 8,936 |
| Los Alamos | New Mexico | 2 | 25,350 | 117 |
| Okeechobee | Florida | 46 | 25,349 | 2,052 |
| Haralson | Georgia | 5 | 25,310 | 217 |
| Tama | Iowa | 13 | 25,305 | 733 |
| Mason | Kentucky | 4 | 25,305 | 491 |
| King George | Virginia | 28 | 25,284 | 2,845 |
| Marshall | Oklahoma | 7 | 25,259 | 1,553 |
| Taos | New Mexico | 95 | 25,233 | 10,807 |
| Garrett | Maryland | 80 | 25,122 | 943 |
| Yazoo | Mississippi | 18 | 25,085 | 6,401 |
| Chattooga | Georgia | 7 | 25,072 | 215 |
| Floyd | Indiana | 4 | 25,067 | 614 |
| Morrison | Minnesota | 97 | 25,033 | 856 |
| Asotin | Washington | 7 | 25,022 | 219 |
| Brown | Indiana | 6 | 24,994 | 790 |
| Pine | Minnesota | 112 | 24,985 | 1,140 |
| Iroquois | Illinois | 62 | 24,975 | 4,282 |
| Calhoun | Texas | 22 | 24,972 | 2,854 |
| Chaffee | Colorado | 70 | 24,956 | 5,369 |
| Warren | Virginia | 32 | 24,952 | 1,071 |
| Champaign | Ohio | 43 | 24,940 | 3,657 |
| Tishomingo | Mississippi | 11 | 24,936 | 2,414 |
| Osceola | Michigan | 98 | 24,917 | 2,154 |
| Mason | Michigan | 87 | 24,895 | 3,061 |
| Taylor | Kentucky | 1 | 24,874 | 516 |
| Coffee | Georgia | 38 | 24,867 | 2,220 |
| Nicholas | West Virginia | 9 | 24,847 | 1,166 |
| Shelby | Indiana | 38 | 24,840 | 3,517 |
| Macon | Alabama | 5 | 24,813 | 532 |
| Ouachita | Arkansas | 12 | 24,786 | 835 |
| McPherson | Kansas | 15 | 24,773 | 625 |
| Clinton | Indiana | 32 | 24,769 | 2,106 |
| Cass | Minnesota | 256 | 24,761 | 990 |
| Lassen | California | 55 | 24,759 | 421 |
| Aibonito Municipio | Puerto Rico | 7 | 24,745 | 2,675 |
| Knox | Kentucky | 2 | 24,733 | 1,378 |
| Codington | South Dakota | 6 | 24,705 | 485 |
| Carlton | Minnesota | 76 | 24,589 | 578 |
| Orange | Virginia | 20 | 24,521 | 1,390 |
| Polk | Minnesota | 66 | 24,497 | 501 |
| Panola | Texas | 22 | 24,493 | 2,618 |
| Neshoba | Mississippi | 6 | 24,485 | 1,568 |
| Richland Parish | Louisiana | 11 | 24,474 | 1,706 |
| Haywood | Tennessee | 10 | 24,451 | 142 |
| McClain | Oklahoma | 13 | 24,400 | 2,005 |
| Jasper | Indiana | 66 | 24,395 | 5,525 |
| Holmes | Ohio | 85 | 24,383 | 6,341 |
| Ottawa | Oklahoma | 19 | 24,382 | 3,716 |
| Howell | Missouri | 17 | 24,372 | 479 |
| Lincoln | Maine | 86 | 24,371 | 6,555 |
| Mason | West Virginia | 12 | 24,359 | 2,722 |
| Johnson | Kentucky | 1 | 24,354 | 581 |
| Hutchinson | Texas | 11 | 24,346 | 643 |
| Coahoma | Mississippi | 18 | 24,296 | 6,880 |
| Edmonson | Kentucky | 3 | 24,289 | 817 |
| Logan | Illinois | 22 | 24,256 | 880 |
| Scott | Tennessee | 4 | 24,255 | 155 |