Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Daggett | Utah | 13 | 3,908 | 1,931 |
| Camuy Municipio | Puerto Rico | 1 | 3,904 | 15 |
| Sharkey | Mississippi | 5 | 3,902 | 3,331 |
| Irwin | Georgia | 6 | 3,888 | 134 |
| Crockett | Texas | 2 | 3,870 | 33 |
| Las Piedras Municipio | Puerto Rico | 8 | 3,864 | 721 |
| Knox | Texas | 8 | 3,857 | 1,379 |
| Scott | Kansas | 4 | 3,823 | 413 |
| Hanson | South Dakota | 3 | 3,814 | 55 |
| Phillips | Kansas | 10 | 3,808 | 1,103 |
| Carlisle | Kentucky | 6 | 3,803 | 2,223 |
| Kimble | Texas | 6 | 3,800 | 420 |
| Kinney | Texas | 6 | 3,795 | 266 |
| Adams | Idaho | 17 | 3,786 | 677 |
| County 10011 | 10 | 3 | 3,783 | 910 |
| Vinton | Ohio | 4 | 3,755 | 246 |
| Rolette | North Dakota | 8 | 3,753 | 271 |
| Carter | Missouri | 9 | 3,732 | 452 |
| Washington | Colorado | 6 | 3,731 | 2,683 |
| Wahkiakum | Washington | 6 | 3,718 | 726 |
| Garfield | Washington | 9 | 3,712 | 352 |
| Sherman | Oregon | 12 | 3,709 | 849 |
| Douglas | Missouri | 10 | 3,677 | 837 |
| County 10065 | 10 | 7 | 3,673 | 2,308 |
| Gray | Kansas | 7 | 3,651 | 563 |
| Stark | Illinois | 10 | 3,649 | 2,058 |
| Scott | Arkansas | 3 | 3,625 | 214 |
| Barber | Kansas | 9 | 3,623 | 580 |
| Harmon | Oklahoma | 3 | 3,602 | 1,371 |
| Madison | Arkansas | 5 | 3,597 | 140 |
| Phillips | Colorado | 4 | 3,593 | 973 |
| Calhoun | West Virginia | 3 | 3,577 | 1,486 |
| Union | Indiana | 14 | 3,557 | 817 |
| Kimball | Nebraska | 7 | 3,544 | 180 |
| Warren | Georgia | 3 | 3,536 | 595 |
| Elliott | Kentucky | 1 | 3,528 | 41 |
| Aguada Municipio | Puerto Rico | 8 | 3,528 | 2,230 |
| County MP030 | Northern Mariana Islands | 3 | 3,513 | 177 |
| Chattahoochee | Georgia | 7 | 3,506 | 60 |
| Griggs | North Dakota | 5 | 3,503 | 157 |
| Lunenburg | Virginia | 5 | 3,495 | 156 |
| Quitman | Georgia | 6 | 3,482 | 221 |
| Trego | Kansas | 5 | 3,479 | 108 |
| Spink | South Dakota | 10 | 3,479 | 1,176 |
| Howard | Nebraska | 8 | 3,468 | 194 |
| Pendleton | West Virginia | 17 | 3,463 | 2,219 |
| Chouteau | Montana | 12 | 3,456 | 3,111 |
| Morrill | Nebraska | 13 | 3,438 | 723 |
| Amelia | Virginia | 8 | 3,393 | 209 |
| Wayne | Iowa | 5 | 3,389 | 1,525 |
| Boone | Nebraska | 8 | 3,378 | 336 |
| Martin | Texas | 5 | 3,378 | 1,558 |
| Mahnomen | Minnesota | 18 | 3,362 | 98 |
| Vega Alta Municipio | Puerto Rico | 2 | 3,344 | 421 |
| Beaver | Oklahoma | 18 | 3,335 | 3,834 |
| Brule | South Dakota | 3 | 3,312 | 153 |
| Woodson | Kansas | 3 | 3,311 | 296 |
| Pulaski | Illinois | 7 | 3,308 | 484 |
| Sutton | Texas | 4 | 3,298 | 246 |
| Audubon | Iowa | 5 | 3,272 | 402 |
| Hall | Texas | 7 | 3,265 | 1,391 |
| Guayama Municipio | Puerto Rico | 3 | 3,251 | 712 |
| County 10055 | 10 | 1 | 3,250 | 45 |
| Meade | Kansas | 5 | 3,236 | 99 |
| Taylor | Iowa | 3 | 3,232 | 476 |
| Clay | Georgia | 7 | 3,226 | 370 |
| Van Buren | Iowa | 7 | 3,195 | 361 |
| Bent | Colorado | 5 | 3,187 | 663 |
| Sullivan | Pennsylvania | 30 | 3,178 | 4,309 |
| Crane | Texas | 2 | 3,175 | 361 |
| County 06081 | 06 | 4 | 3,108 | 48 |
| Goliad | Texas | 6 | 3,091 | 118 |
| Polk | Nebraska | 4 | 3,090 | 196 |
| Reagan | Texas | 3 | 3,065 | 126 |
| Lafayette | Florida | 9 | 3,064 | 1,075 |
| Sheridan | Nebraska | 5 | 3,052 | 126 |
| Crittenden | Kentucky | 1 | 3,039 | 181 |
| Nuckolls | Nebraska | 5 | 3,037 | 331 |
| Crowley | Colorado | 8 | 3,031 | 920 |
| San Juan | Colorado | 4 | 2,994 | 330 |
| Oneida | Idaho | 10 | 2,980 | 218 |
| Lewis | Idaho | 6 | 2,976 | 637 |
| Roanoke | Virginia | 16 | 2,961 | 400 |
| County 10027 | 10 | 9 | 2,948 | 2,623 |
| Davis | Iowa | 2 | 2,946 | 820 |
| Pawnee | Nebraska | 8 | 2,944 | 271 |
| Buchanan | Missouri | 5 | 2,937 | 67 |
| Rappahannock | Virginia | 17 | 2,894 | 2,006 |
| Charles City | Virginia | 21 | 2,887 | 1,209 |
| Costilla | Colorado | 12 | 2,872 | 2,655 |
| Kearny | Kansas | 2 | 2,858 | 153 |
| Chautauqua | Kansas | 10 | 2,840 | 1,223 |
| Musselshell | Montana | 8 | 2,822 | 586 |
| Day | South Dakota | 6 | 2,815 | 432 |
| Haines Borough | Alaska | 5 | 2,798 | 768 |
| Collingsworth | Texas | 4 | 2,792 | 797 |
| Valley | Nebraska | 6 | 2,788 | 378 |
| Phillips | Montana | 12 | 2,773 | 5,597 |
| County 06055 | 06 | 2 | 2,772 | 96 |
| Florence | Wisconsin | 44 | 2,766 | 711 |