Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Stephens | Texas | 4 | 10,669 | 195 |
| Quay | New Mexico | 10 | 10,646 | 569 |
| McCormick | South Carolina | 7 | 10,633 | 205 |
| St. Helena Parish | Louisiana | 6 | 10,609 | 120 |
| Custer | Montana | 11 | 10,579 | 431 |
| Morrow | Ohio | 19 | 10,569 | 1,202 |
| Elbert | Georgia | 16 | 10,563 | 588 |
| Trousdale | Tennessee | 1 | 10,562 | 185 |
| Posey | Indiana | 9 | 10,547 | 1,105 |
| Dawson | Montana | 32 | 10,547 | 6,707 |
| Hormigueros Municipio | Puerto Rico | 1 | 10,541 | 335 |
| Torrance | New Mexico | 27 | 10,538 | 6,677 |
| Southeast Fairbanks Census Area | Alaska | 62 | 10,527 | 7,312 |
| DeKalb | Missouri | 6 | 10,517 | 683 |
| Perry | Alabama | 3 | 10,479 | 448 |
| Marshall | Illinois | 25 | 10,477 | 1,633 |
| Noble | Oklahoma | 11 | 10,436 | 5,202 |
| Runnels | Texas | 5 | 10,421 | 2,316 |
| Nicholas | Kentucky | 3 | 10,410 | 1,091 |
| Bayfield | Wisconsin | 190 | 10,382 | 4,627 |
| Gaines | Texas | 10 | 10,373 | 4,046 |
| King William | Virginia | 24 | 10,356 | 451 |
| Parmer | Texas | 5 | 10,355 | 385 |
| Franklin | Iowa | 20 | 10,347 | 879 |
| Taylor | Wisconsin | 60 | 10,347 | 1,678 |
| Big Horn | Montana | 23 | 10,335 | 6,556 |
| Nome Census Area | Alaska | 17 | 10,325 | 18,055 |
| Henderson | Illinois | 28 | 10,317 | 2,179 |
| Allamakee | Iowa | 32 | 10,314 | 2,085 |
| Dawson | Texas | 4 | 10,313 | 2,604 |
| Johnston | Oklahoma | 13 | 10,296 | 2,143 |
| Telfair | Georgia | 7 | 10,290 | 360 |
| County 06039 | 06 | 7 | 10,285 | 778 |
| Saluda | South Carolina | 16 | 10,276 | 470 |
| Clarke | Iowa | 3 | 10,267 | 241 |
| Grundy | Missouri | 5 | 10,247 | 353 |
| Idaho | Idaho | 58 | 10,236 | 3,546 |
| Kingfisher | Oklahoma | 11 | 10,232 | 4,983 |
| Coleman | Texas | 3 | 10,226 | 456 |
| Carroll | Mississippi | 6 | 10,203 | 3,739 |
| Harrison | Iowa | 20 | 10,200 | 1,284 |
| Nowata | Oklahoma | 12 | 10,195 | 3,923 |
| Clay | Illinois | 9 | 10,181 | 301 |
| Swain | North Carolina | 56 | 10,163 | 5,377 |
| Pennington | Minnesota | 23 | 10,114 | 418 |
| Greene | Alabama | 4 | 10,093 | 315 |
| Jefferson | Montana | 42 | 10,086 | 6,871 |
| Worth | Georgia | 11 | 10,072 | 425 |
| Cook | Georgia | 11 | 10,057 | 592 |
| Charles Mix | South Dakota | 6 | 10,052 | 378 |
| Morgan | Georgia | 16 | 10,028 | 516 |
| Perry | Mississippi | 11 | 10,012 | 6,127 |
| Platte | Wyoming | 28 | 10,003 | 995 |
| Allen | Kansas | 14 | 9,991 | 815 |
| Schuyler | New York | 63 | 9,985 | 3,726 |
| Wabash | Illinois | 6 | 9,981 | 736 |
| County 10009 | 10 | 11 | 9,972 | 1,994 |
| Clay | Tennessee | 2 | 9,947 | 160 |
| Jefferson | Florida | 12 | 9,901 | 574 |
| Moniteau | Missouri | 11 | 9,892 | 823 |
| Breathitt | Kentucky | 3 | 9,872 | 522 |
| Morgan | Kentucky | 2 | 9,869 | 131 |
| Clark | Missouri | 4 | 9,861 | 197 |
| Goshen | Wyoming | 17 | 9,851 | 510 |
| Alger | Michigan | 87 | 9,847 | 1,987 |
| Lewis | Kentucky | 2 | 9,829 | 181 |
| Gem | Idaho | 34 | 9,813 | 1,883 |
| Prince Edward | Virginia | 9 | 9,801 | 126 |
| Marion | Kansas | 14 | 9,799 | 1,406 |
| Maunabo Municipio | Puerto Rico | 6 | 9,788 | 1,760 |
| Garfield | Utah | 53 | 9,783 | 5,624 |
| Washington | Florida | 25 | 9,782 | 320 |
| Lake | South Dakota | 5 | 9,782 | 683 |
| Sibley | Minnesota | 20 | 9,745 | 389 |
| Nottoway | Virginia | 8 | 9,742 | 645 |
| Washburn | Wisconsin | 130 | 9,740 | 1,965 |
| Louisa | Iowa | 22 | 9,731 | 1,727 |
| Camden | North Carolina | 1 | 9,717 | 191 |
| Brewster | Texas | 15 | 9,717 | 1,209 |
| Northumberland | Virginia | 63 | 9,713 | 4,024 |
| Luquillo Municipio | Puerto Rico | 2 | 9,710 | 718 |
| McLean | North Dakota | 13 | 9,697 | 559 |
| Cumberland | Kentucky | 2 | 9,665 | 609 |
| San Juan | Utah | 28 | 9,658 | 5,217 |
| Bleckley | Georgia | 3 | 9,654 | 67 |
| Sitka City and Borough | Alaska | 3 | 9,645 | 934 |
| Okfuskee | Oklahoma | 6 | 9,630 | 4,142 |
| Nemaha | Kansas | 11 | 9,620 | 339 |
| Leslie | Kentucky | 1 | 9,614 | 382 |
| Pike | Georgia | 12 | 9,595 | 622 |
| Koochiching | Minnesota | 34 | 9,592 | 493 |
| Randolph | Arkansas | 10 | 9,572 | 412 |
| Coffey | Kansas | 9 | 9,572 | 628 |
| Deer Lodge | Montana | 15 | 9,563 | 2,034 |
| Dallam | Texas | 7 | 9,562 | 718 |
| Choctaw | Mississippi | 11 | 9,558 | 2,705 |
| Yancey | North Carolina | 27 | 9,527 | 2,598 |
| Gooding | Idaho | 26 | 9,512 | 1,336 |
| Rock | Minnesota | 8 | 9,495 | 119 |
| Beaverhead | Montana | 48 | 9,494 | 6,629 |