Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Plaquemines Parish | Louisiana | 5 | 32,282 | 630 |
| Knox | Indiana | 18 | 32,275 | 2,537 |
| Newaygo | Michigan | 148 | 32,254 | 4,093 |
| Henderson | Tennessee | 4 | 32,235 | 202 |
| Allen Parish | Louisiana | 10 | 32,217 | 714 |
| Harvey | Kansas | 14 | 32,039 | 489 |
| Laclede | Missouri | 15 | 32,039 | 1,231 |
| Miller | Arkansas | 12 | 32,038 | 717 |
| Morehouse Parish | Louisiana | 15 | 31,947 | 1,958 |
| Prentiss | Mississippi | 12 | 31,943 | 6,370 |
| Queen Anne's | Maryland | 100 | 31,903 | 1,478 |
| Noble | Indiana | 104 | 31,881 | 6,408 |
| Montezuma | Colorado | 18 | 31,851 | 1,218 |
| Madison | New York | 94 | 31,708 | 2,802 |
| Stephens | Georgia | 5 | 31,655 | 226 |
| Pickens | Georgia | 7 | 31,634 | 221 |
| Mercer | West Virginia | 13 | 31,615 | 18,223 |
| Obion | Tennessee | 11 | 31,591 | 558 |
| DeKalb | Indiana | 48 | 31,561 | 2,628 |
| Clinton | Pennsylvania | 31 | 31,527 | 10,921 |
| Adams | Ohio | 6 | 31,497 | 140 |
| Pulaski | Virginia | 25 | 31,466 | 2,486 |
| Warren | Pennsylvania | 65 | 31,457 | 6,530 |
| Preston | West Virginia | 75 | 31,431 | 4,723 |
| Pointe Coupee Parish | Louisiana | 12 | 31,294 | 348 |
| Scotts Bluff | Nebraska | 29 | 31,247 | 1,712 |
| Wyoming | New York | 91 | 31,166 | 1,799 |
| Winston | Alabama | 5 | 31,131 | 362 |
| Delaware | New York | 140 | 31,097 | 12,320 |
| Grant | Kentucky | 4 | 31,082 | 541 |
| Johnson | Arkansas | 12 | 31,064 | 333 |
| Henry | Virginia | 22 | 31,038 | 1,209 |
| Oceana | Michigan | 134 | 31,037 | 2,890 |
| Stokes | North Carolina | 48 | 31,017 | 5,889 |
| Nicollet | Minnesota | 26 | 30,952 | 217 |
| Jefferson | Pennsylvania | 42 | 30,935 | 5,662 |
| Douglas | Minnesota | 153 | 30,896 | 1,199 |
| Culpeper | Virginia | 53 | 30,893 | 7,846 |
| West Baton Rouge Parish | Louisiana | 7 | 30,886 | 377 |
| Surry | North Carolina | 115 | 30,850 | 10,400 |
| McLeod | Minnesota | 39 | 30,778 | 363 |
| Itasca | Minnesota | 229 | 30,771 | 1,273 |
| Wyoming | Pennsylvania | 98 | 30,751 | 24,661 |
| Uvalde | Texas | 30 | 30,707 | 2,564 |
| Edgecombe | North Carolina | 9 | 30,693 | 972 |
| Knox | Maine | 47 | 30,692 | 3,529 |
| Hardin | Tennessee | 6 | 30,692 | 225 |
| Lyon | Kansas | 12 | 30,663 | 467 |
| Ravalli | Montana | 129 | 30,657 | 9,816 |
| Union | South Carolina | 9 | 30,650 | 356 |
| Ripley | Indiana | 10 | 30,624 | 880 |
| Wakulla | Florida | 11 | 30,574 | 408 |
| Montgomery | Kansas | 17 | 30,553 | 2,176 |
| Marshall | West Virginia | 14 | 30,546 | 2,196 |
| Hale | Texas | 21 | 30,539 | 2,647 |
| La Paz | Arizona | 83 | 30,510 | 8,301 |
| Mercer | Ohio | 77 | 30,475 | 3,474 |
| Del Norte | California | 32 | 30,424 | 518 |
| Logan | Kentucky | 7 | 30,357 | 744 |
| Phelps | Missouri | 29 | 30,350 | 2,509 |
| Graves | Kentucky | 11 | 30,322 | 2,724 |
| Marion | Iowa | 14 | 30,305 | 760 |
| Perry | Kentucky | 3 | 30,247 | 766 |
| Mifflin | Pennsylvania | 28 | 30,153 | 2,717 |
| Hillsdale | Michigan | 99 | 30,144 | 1,593 |
| Talbot | Maryland | 41 | 30,121 | 1,179 |
| Boone | Indiana | 31 | 30,056 | 2,632 |
| Greenbrier | West Virginia | 36 | 30,047 | 10,134 |
| DeKalb | Tennessee | 6 | 29,977 | 657 |
| Copiah | Mississippi | 16 | 29,961 | 5,783 |
| Monroe | Georgia | 11 | 29,960 | 556 |
| Livingston | Illinois | 37 | 29,921 | 1,890 |
| McCurtain | Oklahoma | 16 | 29,914 | 3,203 |
| Randolph | Illinois | 22 | 29,863 | 2,566 |
| Graham | Arizona | 16 | 29,739 | 3,328 |
| Morton | North Dakota | 13 | 29,721 | 464 |
| Lares Municipio | Puerto Rico | 6 | 29,715 | 3,660 |
| Montgomery | North Carolina | 19 | 29,684 | 1,570 |
| Claiborne | Tennessee | 7 | 29,671 | 507 |
| Edgefield | South Carolina | 9 | 29,621 | 113 |
| Montgomery | Indiana | 49 | 29,560 | 6,607 |
| Colquitt | Georgia | 43 | 29,558 | 2,032 |
| Adams | Nebraska | 16 | 29,551 | 598 |
| Dawson | Georgia | 11 | 29,548 | 336 |
| Wharton | Texas | 31 | 29,486 | 2,142 |
| Barry | Missouri | 93 | 29,480 | 5,549 |
| Logan | Arkansas | 18 | 29,464 | 1,435 |
| Union | Georgia | 28 | 29,443 | 997 |
| Rio Arriba | New Mexico | 63 | 29,347 | 14,535 |
| Barron | Wisconsin | 190 | 29,256 | 4,239 |
| Wabash | Indiana | 50 | 29,234 | 2,402 |
| Jackson | Oklahoma | 11 | 29,205 | 2,827 |
| Salinas Municipio | Puerto Rico | 9 | 29,177 | 2,288 |
| Christian | Illinois | 24 | 29,156 | 933 |
| Susquehanna | Pennsylvania | 115 | 29,137 | 15,681 |
| Bureau | Illinois | 56 | 29,118 | 6,440 |
| Sabana Grande Municipio | Puerto Rico | 2 | 29,084 | 675 |
| Houston | Texas | 10 | 29,066 | 586 |
| Miami | Kansas | 8 | 29,041 | 1,084 |
| Freeborn | Minnesota | 58 | 29,013 | 771 |