Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Jefferson | Washington | 70 | 46,719 | 8,616 |
| Washington | Pennsylvania | 33 | 46,691 | 7,539 |
| Baltimore | Maryland | 276 | 46,635 | 3,504 |
| Greene | Pennsylvania | 9 | 46,500 | 1,470 |
| Lawrence | Indiana | 6 | 46,335 | 1,011 |
| Fulton | New York | 114 | 46,257 | 12,513 |
| Val Verde | Texas | 37 | 46,250 | 6,858 |
| Genesee | New York | 30 | 46,182 | 413 |
| Brown | Texas | 8 | 46,048 | 314 |
| Campbell | Tennessee | 9 | 45,790 | 1,281 |
| Shiawassee | Michigan | 142 | 45,777 | 4,115 |
| Ogle | Illinois | 112 | 45,754 | 8,348 |
| Atascosa | Texas | 12 | 45,736 | 662 |
| Boone | Illinois | 56 | 45,698 | 2,853 |
| Washington | Oklahoma | 11 | 45,692 | 1,820 |
| Okmulgee | Oklahoma | 15 | 45,674 | 7,090 |
| Otsego | New York | 196 | 45,582 | 12,144 |
| Kay | Oklahoma | 14 | 45,560 | 1,384 |
| Hancock | Indiana | 60 | 45,547 | 4,984 |
| Pickaway | Ohio | 40 | 45,484 | 4,202 |
| Macoupin | Illinois | 37 | 45,357 | 3,529 |
| St. Bernard Parish | Louisiana | 2 | 45,143 | 447 |
| Ohio | West Virginia | 5 | 45,020 | 732 |
| Burnet | Texas | 70 | 44,930 | 10,240 |
| Iberville Parish | Louisiana | 13 | 44,903 | 388 |
| Madison | Ohio | 59 | 44,857 | 6,897 |
| Bennington | Vermont | 124 | 44,748 | 11,101 |
| Otter Tail | Minnesota | 282 | 44,731 | 1,791 |
| Augusta | Virginia | 41 | 44,697 | 1,056 |
| Santa Isabel Municipio | Puerto Rico | 5 | 44,670 | 1,017 |
| Natchitoches Parish | Louisiana | 14 | 44,641 | 3,262 |
| Kendall | Texas | 49 | 44,641 | 4,506 |
| Hopkins | Texas | 14 | 44,614 | 863 |
| Mayes | Oklahoma | 23 | 44,551 | 5,289 |
| County 10061 | 10 | 12 | 44,469 | 1,960 |
| Chesterfield | South Carolina | 12 | 44,401 | 373 |
| Floyd | Kentucky | 5 | 44,358 | 1,488 |
| Halifax | North Carolina | 12 | 44,334 | 2,198 |
| Logan | Ohio | 135 | 44,127 | 7,646 |
| Cooke | Texas | 25 | 44,108 | 5,993 |
| Okanogan | Washington | 123 | 44,103 | 7,257 |
| Washington | New York | 118 | 44,071 | 12,275 |
| Goodhue | Minnesota | 91 | 44,002 | 1,061 |
| Essex | New York | 137 | 43,892 | 6,808 |
| Henry | Illinois | 77 | 43,864 | 5,798 |
| Baldwin | Georgia | 5 | 43,822 | 184 |
| Lonoke | Arkansas | 14 | 43,740 | 495 |
| Wise | Texas | 60 | 43,731 | 8,175 |
| Duplin | North Carolina | 20 | 43,574 | 3,044 |
| Buffalo | Nebraska | 43 | 43,401 | 1,147 |
| Amador | California | 71 | 43,392 | 1,026 |
| Evangeline Parish | Louisiana | 14 | 43,375 | 1,193 |
| Escambia | Alabama | 9 | 43,326 | 1,565 |
| Dallas | Alabama | 8 | 43,295 | 286 |
| Des Moines | Iowa | 11 | 43,192 | 768 |
| Pasquotank | North Carolina | 4 | 43,187 | 33 |
| Highland | Ohio | 9 | 42,930 | 677 |
| Marion | Illinois | 18 | 42,837 | 810 |
| Ottawa | Ohio | 37 | 42,830 | 2,556 |
| Silver Bow | Montana | 23 | 42,630 | 2,525 |
| Vilas | Wisconsin | 466 | 42,533 | 4,566 |
| Franklin | Illinois | 25 | 42,504 | 808 |
| Gibson | Tennessee | 15 | 42,504 | 473 |
| Lincoln | Missouri | 47 | 42,497 | 2,765 |
| Palo Pinto | Texas | 17 | 42,483 | 2,324 |
| Dukes | Massachusetts | 25 | 42,168 | 1,211 |
| Fannin | Texas | 23 | 42,114 | 1,513 |
| Venango | Pennsylvania | 69 | 41,982 | 8,381 |
| Mississippi | Arkansas | 23 | 41,872 | 775 |
| Clatsop | Oregon | 31 | 41,699 | 5,305 |
| Union | Ohio | 37 | 41,647 | 2,492 |
| Grant | Wisconsin | 89 | 41,605 | 3,251 |
| Thomas | Georgia | 35 | 41,580 | 1,291 |
| Yauco Municipio | Puerto Rico | 10 | 41,494 | 3,897 |
| Marshall | Tennessee | 4 | 41,362 | 298 |
| Latah | Idaho | 35 | 41,303 | 2,229 |
| Harrison | Indiana | 8 | 41,282 | 526 |
| Whiteside | Illinois | 62 | 41,278 | 1,695 |
| Brookings | South Dakota | 12 | 41,264 | 2,574 |
| Whitley | Kentucky | 5 | 41,263 | 497 |
| Monroe | Mississippi | 13 | 41,263 | 7,738 |
| County 09073 | 09 | 10 | 41,233 | 1,205 |
| Siskiyou | California | 72 | 41,230 | 993 |
| Lincoln | Tennessee | 4 | 41,182 | 371 |
| Coos | New Hampshire | 113 | 41,156 | 7,377 |
| Juncos Municipio | Puerto Rico | 3 | 41,043 | 2,524 |
| Pike | Alabama | 5 | 41,022 | 656 |
| Manati Municipio | Puerto Rico | 7 | 40,999 | 892 |
| Hendry | Florida | 42 | 40,888 | 1,413 |
| Cheatham | Tennessee | 4 | 40,883 | 163 |
| Steuben | Indiana | 145 | 40,851 | 6,810 |
| Bladen | North Carolina | 25 | 40,804 | 3,547 |
| Hot Spring | Arkansas | 9 | 40,747 | 293 |
| Huntingdon | Pennsylvania | 91 | 40,685 | 17,448 |
| Upshur | Texas | 15 | 40,615 | 1,447 |
| Aroostook | Maine | 124 | 40,588 | 14,153 |
| Juneau City and Borough | Alaska | 11 | 40,575 | 2,414 |
| Oneida | Wisconsin | 346 | 40,522 | 4,836 |
| Greenup | Kentucky | 7 | 40,510 | 1,573 |
| Sequoyah | Oklahoma | 15 | 40,394 | 1,738 |