Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Sheridan | Montana | 8 | 2,764 | 1,493 |
| Osborne | Kansas | 7 | 2,755 | 736 |
| Coke | Texas | 6 | 2,755 | 1,341 |
| Upton | Texas | 4 | 2,731 | 281 |
| Bland | Virginia | 6 | 2,721 | 317 |
| Keweenaw | Michigan | 19 | 2,701 | 545 |
| Wheatland | Montana | 8 | 2,697 | 546 |
| Dewey | Oklahoma | 8 | 2,690 | 919 |
| Jeff Davis | Texas | 11 | 2,679 | 1,096 |
| Nance | Nebraska | 7 | 2,674 | 220 |
| Blaine | Montana | 12 | 2,672 | 3,819 |
| Chase | Nebraska | 4 | 2,670 | 211 |
| Roger Mills | Oklahoma | 7 | 2,649 | 1,137 |
| County 09109 | 09 | 2 | 2,630 | 35 |
| Smith | Kansas | 5 | 2,618 | 378 |
| County 10041 | 10 | 3 | 2,615 | 51 |
| Foster | North Dakota | 3 | 2,611 | 50 |
| Hancock | Tennessee | 1 | 2,607 | 197 |
| County 09107 | 09 | 2 | 2,585 | 786 |
| Stafford | Kansas | 3 | 2,583 | 159 |
| Worth | Missouri | 3 | 2,582 | 206 |
| County 10047 | 10 | 5 | 2,580 | 269 |
| Appomattox | Virginia | 12 | 2,574 | 470 |
| Ellis | Oklahoma | 7 | 2,569 | 1,949 |
| Jewell | Kansas | 7 | 2,554 | 909 |
| Lipscomb | Texas | 4 | 2,554 | 1,018 |
| Traverse | Minnesota | 12 | 2,510 | 238 |
| Baca | Colorado | 6 | 2,504 | 1,064 |
| Harper | Oklahoma | 3 | 2,495 | 1,292 |
| Webster | Nebraska | 5 | 2,431 | 230 |
| Haskell | Kansas | 2 | 2,421 | 108 |
| Hemphill | Texas | 2 | 2,400 | 59 |
| Red Lake | Minnesota | 12 | 2,395 | 145 |
| County 09045 | 09 | 7 | 2,388 | 676 |
| Catron | New Mexico | 15 | 2,383 | 1,637 |
| Elk | Kansas | 6 | 2,353 | 1,750 |
| Rush | Kansas | 9 | 2,335 | 1,426 |
| Harlan | Nebraska | 13 | 2,329 | 495 |
| Western District | American Samoa | 71 | 2,327 | 48 |
| Sherman | Texas | 3 | 2,322 | 77 |
| McHenry | North Dakota | 7 | 2,316 | 432 |
| Franklin | Nebraska | 8 | 2,304 | 720 |
| De Baca | New Mexico | 4 | 2,293 | 469 |
| LaMoure | North Dakota | 10 | 2,292 | 649 |
| Morton | Kansas | 3 | 2,289 | 165 |
| Wirt | West Virginia | 1 | 2,289 | 170 |
| Lincoln | Idaho | 4 | 2,286 | 391 |
| Ringgold | Iowa | 3 | 2,268 | 748 |
| County 04011 | 04 | 1 | 2,266 | 0 |
| Brown | Nebraska | 5 | 2,263 | 266 |
| Jackson | Colorado | 14 | 2,253 | 390 |
| Mills | Texas | 4 | 2,244 | 857 |
| Lake and Peninsula Borough | Alaska | 16 | 2,235 | 9,945 |
| Mason | Texas | 1 | 2,228 | 665 |
| St. John Island | US Virgin Islands | 10 | 2,228 | 22 |
| Logan | Kansas | 2 | 2,210 | 174 |
| Cumberland | Virginia | 5 | 2,195 | 143 |
| Fallon | Montana | 4 | 2,185 | 1,304 |
| Sargent | North Dakota | 5 | 2,183 | 192 |
| Gregory | South Dakota | 4 | 2,160 | 172 |
| Edwards | Texas | 2 | 2,136 | 820 |
| Marshall | South Dakota | 7 | 2,134 | 1,217 |
| County 09089 | 09 | 2 | 2,105 | 370 |
| Edwards | Kansas | 4 | 2,077 | 238 |
| Perkins | Nebraska | 5 | 2,059 | 366 |
| Cochran | Texas | 3 | 2,055 | 805 |
| Cimarron | Oklahoma | 6 | 2,023 | 1,096 |
| Ness | Kansas | 6 | 2,002 | 576 |
| Miller | Georgia | 1 | 1,998 | 100 |
| County 09043 | 09 | 2 | 1,986 | 29 |
| Sherman | Nebraska | 10 | 1,978 | 347 |
| Hamilton | Kansas | 3 | 1,965 | 457 |
| Schleicher | Texas | 1 | 1,951 | 75 |
| Doddridge | West Virginia | 2 | 1,943 | 405 |
| Piute | Utah | 12 | 1,938 | 1,742 |
| Perkins | South Dakota | 3 | 1,936 | 214 |
| Hickman | Kentucky | 2 | 1,933 | 1,074 |
| Hitchcock | Nebraska | 8 | 1,930 | 457 |
| Bowman | North Dakota | 3 | 1,920 | 34 |
| McIntosh | North Dakota | 5 | 1,917 | 204 |
| Oldham | Texas | 5 | 1,884 | 931 |
| Decatur | Kansas | 3 | 1,878 | 490 |
| Gove | Kansas | 6 | 1,861 | 342 |
| Craig | Virginia | 6 | 1,858 | 274 |
| Liberty | Montana | 8 | 1,827 | 704 |
| Meagher | Montana | 8 | 1,825 | 2,288 |
| Sedgwick | Colorado | 4 | 1,794 | 422 |
| Cheyenne | Kansas | 2 | 1,729 | 50 |
| Chase | Kansas | 7 | 1,728 | 862 |
| Garfield | Nebraska | 10 | 1,724 | 110 |
| Frontier | Nebraska | 8 | 1,722 | 400 |
| Graham | Kansas | 4 | 1,700 | 544 |
| County 10069 | 10 | 5 | 1,685 | 1,088 |
| County NN006 | Navajo Nation | 4 | 1,681 | 2,483 |
| McMullen | Texas | 3 | 1,677 | 444 |
| Glascock | Georgia | 3 | 1,673 | 503 |
| Lincoln | Kansas | 4 | 1,658 | 830 |
| Garden | Nebraska | 5 | 1,635 | 98 |
| County 10059 | 10 | 4 | 1,623 | 1,093 |
| County NN053 | Navajo Nation | 4 | 1,623 | 2,428 |