Water Quality by County
3,254 counties with public water systems.
| County | State | Systems | Population | Violations |
|---|---|---|---|---|
| Polk | Florida | 402 | 672,690 | 16,587 |
| Douglas | Nebraska | 53 | 672,690 | 882 |
| Middlesex | New Jersey | 35 | 668,615 | 2,949 |
| Johnson | Kansas | 9 | 668,443 | 321 |
| District of Columbia | District of Columbia | 5 | 667,575 | 263 |
| Tulsa | Oklahoma | 15 | 666,353 | 1,073 |
| Bernalillo | New Mexico | 82 | 651,858 | 15,222 |
| East Baton Rouge Parish | Louisiana | 19 | 650,087 | 566 |
| Providence | Rhode Island | 182 | 642,474 | 14,067 |
| Barnstable | Massachusetts | 127 | 628,756 | 2,953 |
| Cass | Missouri | 31 | 625,744 | 1,771 |
| Will | Illinois | 330 | 622,572 | 37,818 |
| Spokane | Washington | 164 | 621,798 | 9,829 |
| Kent | Michigan | 407 | 616,574 | 4,140 |
| Clark | Washington | 72 | 615,931 | 9,864 |
| Onondaga | New York | 88 | 615,889 | 2,561 |
| Knox | Tennessee | 9 | 601,914 | 406 |
| Bucks | Pennsylvania | 299 | 599,107 | 59,577 |
| Washington | Oregon | 96 | 597,244 | 7,314 |
| Kane | Illinois | 191 | 592,544 | 12,844 |
| Ramsey | Minnesota | 43 | 579,780 | 369 |
| Jefferson | Colorado | 113 | 577,729 | 5,182 |
| Plymouth | Massachusetts | 129 | 574,062 | 4,809 |
| Anne Arundel | Maryland | 425 | 567,204 | 5,956 |
| Contra Costa | California | 86 | 565,242 | 1,010 |
| Madison | Alabama | 9 | 557,706 | 1,075 |
| Volusia | Florida | 135 | 554,868 | 4,719 |
| Polk | Iowa | 38 | 552,627 | 1,563 |
| New Castle | Delaware | 76 | 541,043 | 1,173 |
| Lake | Indiana | 108 | 539,424 | 12,533 |
| Orleans | New York | 23 | 535,814 | 437 |
| Cape May | New Jersey | 165 | 535,566 | 7,106 |
| Montgomery | Ohio | 74 | 529,379 | 4,724 |
| Larimer | Colorado | 136 | 519,497 | 9,218 |
| Dane | Wisconsin | 301 | 517,785 | 7,065 |
| Stanislaus | California | 195 | 511,603 | 3,426 |
| Ada | Idaho | 87 | 511,181 | 5,380 |
| Seminole | Florida | 60 | 510,279 | 3,348 |
| Passaic | New Jersey | 151 | 506,286 | 10,406 |
| Pinal | Arizona | 94 | 505,241 | 20,790 |
| Greenville | South Carolina | 45 | 498,460 | 567 |
| Sedgwick | Kansas | 29 | 498,426 | 1,514 |
| Washoe | Nevada | 72 | 494,328 | 6,370 |
| Santa Barbara | California | 152 | 490,541 | 2,187 |
| Guilford | North Carolina | 202 | 489,022 | 30,107 |
| Sarasota | Florida | 82 | 486,996 | 992 |
| Sonoma | California | 440 | 481,120 | 6,052 |
| Charleston | South Carolina | 74 | 480,067 | 846 |
| Monterey | California | 315 | 476,400 | 13,641 |
| Solano | California | 61 | 470,297 | 530 |
| Summit | Ohio | 214 | 467,695 | 17,163 |
| Pulaski | Arkansas | 31 | 461,701 | 900 |
| Mobile | Alabama | 15 | 461,024 | 2,918 |
| Atlantic | New Jersey | 195 | 452,348 | 8,907 |
| Morris | New Jersey | 304 | 450,101 | 24,499 |
| Tulare | California | 296 | 446,656 | 12,135 |
| Cameron | Texas | 30 | 441,125 | 2,774 |
| Jefferson Parish | Louisiana | 4 | 440,987 | 247 |
| Hampden | Massachusetts | 115 | 440,281 | 3,254 |
| Hudson | New Jersey | 6 | 435,495 | 332 |
| Manatee | Florida | 52 | 435,178 | 781 |
| Loudoun | Virginia | 102 | 433,414 | 4,980 |
| Lucas | Ohio | 46 | 433,198 | 3,569 |
| Rutherford | Tennessee | 5 | 433,004 | 394 |
| Placer | California | 123 | 429,603 | 1,542 |
| Boulder | Colorado | 82 | 428,472 | 7,231 |
| Lake | Florida | 272 | 425,924 | 9,501 |
| Washtenaw | Michigan | 264 | 420,450 | 6,092 |
| Bell | Texas | 30 | 418,473 | 1,709 |
| Douglas | Colorado | 73 | 417,473 | 7,411 |
| Horry | South Carolina | 53 | 416,612 | 307 |
| Prince William | Virginia | 45 | 416,494 | 1,444 |
| Pasco | Florida | 210 | 413,604 | 6,345 |
| Hamilton | Tennessee | 11 | 412,782 | 324 |
| Davis | Utah | 25 | 411,806 | 3,162 |
| Orange | New York | 449 | 409,417 | 85,938 |
| Lancaster | Pennsylvania | 434 | 406,457 | 39,193 |
| Brazoria | Texas | 326 | 406,255 | 25,596 |
| Jackson | Missouri | 23 | 405,266 | 559 |
| Galveston | Texas | 57 | 402,181 | 3,917 |
| Thurston | Washington | 322 | 395,780 | 24,330 |
| Forsyth | North Carolina | 19 | 392,063 | 2,199 |
| Dakota | Minnesota | 135 | 391,434 | 1,282 |
| Chesterfield | Virginia | 9 | 390,851 | 331 |
| York | Pennsylvania | 208 | 389,602 | 25,528 |
| Orleans Parish | Louisiana | 10 | 389,093 | 157 |
| Clackamas | Oregon | 231 | 385,530 | 18,114 |
| Sussex | Delaware | 251 | 382,938 | 4,772 |
| Collier | Florida | 44 | 382,648 | 1,949 |
| Berks | Pennsylvania | 493 | 382,268 | 54,767 |
| Butler | Ohio | 22 | 378,755 | 1,035 |
| Benton | Arkansas | 58 | 374,691 | 2,082 |
| Nueces | Texas | 20 | 371,249 | 1,309 |
| Marion | Oregon | 196 | 370,079 | 19,281 |
| Richland | South Carolina | 77 | 361,654 | 5,612 |
| Weld | Colorado | 77 | 359,543 | 4,558 |
| Cumberland | North Carolina | 90 | 349,358 | 9,862 |
| Escambia | Florida | 16 | 348,012 | 370 |
| San Luis Obispo | California | 167 | 347,560 | 1,652 |
| Montgomery | Tennessee | 7 | 344,788 | 413 |