Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| County AK275 | Alaska | 3 | 5,933 | 1,246 |
| Lemhi | Idaho | 44 | 5,930 | 1,447 |
| County 10067 | 10 | 5 | 5,920 | 1,750 |
| Greer | Oklahoma | 7 | 5,906 | 2,003 |
| Bath | Virginia | 13 | 5,905 | 298 |
| Oglethorpe | Georgia | 19 | 5,904 | 1,072 |
| Bottineau | North Dakota | 21 | 5,903 | 867 |
| Holt | Missouri | 7 | 5,896 | 286 |
| Pawnee | Kansas | 6 | 5,887 | 358 |
| Greene | Iowa | 5 | 5,869 | 1,065 |
| Emmons | North Dakota | 6 | 5,867 | 178 |
| Custer | Idaho | 58 | 5,848 | 1,289 |
| Floyd | Virginia | 26 | 5,845 | 1,637 |
| Castro | Texas | 4 | 5,844 | 1,397 |
| Ballard | Kentucky | 6 | 5,837 | 1,618 |
| Surry | Virginia | 22 | 5,822 | 1,098 |
| Jack | Texas | 6 | 5,821 | 896 |
| Keokuk | Iowa | 11 | 5,806 | 535 |
| Wilcox | Georgia | 5 | 5,787 | 259 |
| Kingsbury | South Dakota | 7 | 5,786 | 523 |
| Bayamon Municipio | Puerto Rico | 2 | 5,785 | 207 |
| Rio Blanco | Colorado | 10 | 5,772 | 923 |
| Swisher | Texas | 4 | 5,751 | 297 |
| Iron | Wisconsin | 57 | 5,745 | 1,658 |
| Morgan | West Virginia | 24 | 5,743 | 5,652 |
| Brooks | Texas | 4 | 5,738 | 220 |
| Love | Oklahoma | 9 | 5,735 | 616 |
| Gilmer | West Virginia | 7 | 5,731 | 893 |
| Brown | Illinois | 5 | 5,721 | 154 |
| Benton | Mississippi | 6 | 5,717 | 2,385 |
| Fremont | Iowa | 13 | 5,711 | 996 |
| Knox | Nebraska | 18 | 5,696 | 664 |
| Patrick | Virginia | 37 | 5,696 | 1,587 |
| Nevada | Arkansas | 3 | 5,680 | 156 |
| Brantley | Georgia | 15 | 5,677 | 455 |
| Murray | Minnesota | 28 | 5,671 | 495 |
| Pocahontas | Iowa | 12 | 5,668 | 1,154 |
| Alleghany | North Carolina | 21 | 5,665 | 2,237 |
| Clay | Nebraska | 14 | 5,582 | 1,111 |
| Baraga | Michigan | 23 | 5,580 | 469 |
| Hamilton | Texas | 6 | 5,560 | 270 |
| Johnson | Wyoming | 13 | 5,523 | 351 |
| Modoc | California | 15 | 5,500 | 147 |
| Candler | Georgia | 11 | 5,496 | 252 |
| Gilchrist | Florida | 31 | 5,493 | 707 |
| Lincoln | Nevada | 17 | 5,474 | 1,201 |
| Montgomery | Georgia | 11 | 5,470 | 2,216 |
| Seminole | Georgia | 10 | 5,466 | 549 |
| Menifee | Kentucky | 3 | 5,451 | 157 |
| Baylor | Texas | 2 | 5,414 | 107 |
| Jim Hogg | Texas | 1 | 5,397 | 506 |
| Wallowa | Oregon | 10 | 5,391 | 1,150 |
| Shackelford | Texas | 3 | 5,389 | 498 |
| Union | Florida | 12 | 5,387 | 262 |
| Haskell | Texas | 9 | 5,363 | 2,411 |
| Owsley | Kentucky | 1 | 5,346 | 383 |
| Ontonagon | Michigan | 26 | 5,345 | 768 |
| Putnam | Missouri | 4 | 5,342 | 165 |
| Clay | West Virginia | 6 | 5,324 | 1,545 |
| Ida | Iowa | 7 | 5,309 | 702 |
| Mineral | Colorado | 16 | 5,281 | 1,196 |
| County 10019 | 10 | 11 | 5,280 | 3,295 |
| Ottawa | Kansas | 7 | 5,267 | 609 |
| Washington | Kansas | 12 | 5,258 | 995 |
| Bailey | Texas | 3 | 5,248 | 1,002 |
| County 09009 | 09 | 2 | 5,245 | 531 |
| Calhoun | Georgia | 6 | 5,240 | 288 |
| Bollinger | Missouri | 16 | 5,234 | 548 |
| Harney | Oregon | 11 | 5,233 | 683 |
| Crosby | Texas | 6 | 5,217 | 360 |
| Rich | Utah | 22 | 5,207 | 2,716 |
| Warren | Indiana | 24 | 5,201 | 1,734 |
| County 10045 | 10 | 4 | 5,189 | 825 |
| Dallas | Missouri | 17 | 5,189 | 1,488 |
| Woodruff | Arkansas | 5 | 5,186 | 473 |
| County 10035 | 10 | 11 | 5,183 | 1,392 |
| Scotland | Missouri | 2 | 5,182 | 116 |
| Bristol Bay Borough | Alaska | 30 | 5,169 | 3,437 |
| Butler | Nebraska | 15 | 5,169 | 672 |
| Wheeler | Georgia | 4 | 5,168 | 156 |
| Refugio | Texas | 6 | 5,148 | 870 |
| Kittson | Minnesota | 8 | 5,075 | 79 |
| Essex | Vermont | 18 | 5,070 | 2,359 |
| Calhoun | Florida | 8 | 5,069 | 191 |
| Montgomery | Arkansas | 12 | 5,061 | 2,670 |
| Schley | Georgia | 2 | 5,058 | 58 |
| Sharp | Arkansas | 12 | 5,056 | 1,019 |
| Putnam | Illinois | 22 | 5,039 | 3,447 |
| Lake of the Woods | Minnesota | 66 | 5,031 | 1,072 |
| Charlotte | Virginia | 13 | 5,025 | 618 |
| Floyd | Texas | 4 | 5,010 | 232 |
| County 09039 | 09 | 1 | 5,000 | 9 |
| County 10073 | 10 | 7 | 4,974 | 1,838 |
| Knox | Missouri | 2 | 4,961 | 88 |
| Teton | Montana | 16 | 4,952 | 2,806 |
| Wabaunsee | Kansas | 10 | 4,939 | 716 |
| Republic | Kansas | 10 | 4,932 | 858 |
| Major | Oklahoma | 9 | 4,901 | 2,586 |
| Morris | Kansas | 6 | 4,859 | 305 |
| Lucas | Iowa | 2 | 4,858 | 629 |