Washington water quality by county
39 counties with public water systems. Pick a county to see every system that serves it.
| County | Active systems | People served | Share with violations, 3 yr | Serious violators | Health flags |
|---|---|---|---|---|---|
| Adams County | 48 | 22,385 | 0 | 0 | |
| Asotin County | 7 | 25,022 | 0 | 0 | |
| Benton County | 115 | 289,544 | 4 | 2 | |
| Chelan County | 133 | 123,199 | 0 | 0 | |
| Clallam County | 101 | 88,076 | 1 | 0 | |
| Clark County | 72 | 653,450 | 0 | 0 | |
| Columbia County | 12 | 4,639 | 0 | 0 | |
| Cowlitz County | 77 | 125,351 | 0 | 1 | |
| Douglas County | 46 | 40,758 | 0 | 0 | |
| Ferry County | 33 | 5,999 | 0 | 1 | |
| Franklin County | 81 | 132,285 | 1 | 0 | |
| Garfield County | 9 | 3,712 | 0 | 0 | |
| Grant County | 267 | 123,916 | 1 | 0 | |
| Grays Harbor County | 87 | 89,028 | 1 | 0 | |
| Island County | 308 | 103,155 | 5 | 2 | |
| Jefferson County | 69 | 47,098 | 0 | 1 | |
| King County | 217 | 3,322,257 | 0 | 0 | |
| Kitsap County | 221 | 343,245 | 0 | 0 | |
| Kittitas County | 105 | 50,542 | 0 | 0 | |
| Klickitat County | 55 | 23,040 | 0 | 0 | |
| Lewis County | 167 | 89,246 | 0 | 0 | |
| Lincoln County | 35 | 20,722 | 0 | 0 | |
| Mason County | 242 | 76,405 | 2 | 0 | |
| Okanogan County | 123 | 45,838 | 2 | 0 | |
| Pacific County | 38 | 33,726 | 0 | 0 | |
| Pend Oreille County | 44 | 11,407 | 0 | 1 | |
| Pierce County | 357 | 1,194,353 | 1 | 2 | |
| San Juan County | 111 | 40,117 | 1 | 0 | |
| Skagit County | 86 | 159,409 | 0 | 0 | |
| Skamania County | 58 | 18,824 | 0 | 0 | |
| Snohomish County | 169 | 1,035,980 | 0 | 0 | |
| Spokane County | 166 | 631,205 | 0 | 0 | |
| Stevens County | 69 | 33,694 | 1 | 1 | |
| Thurston County | 322 | 397,526 | 0 | 1 | |
| Wahkiakum County | 6 | 3,726 | 0 | 0 | |
| Walla Walla County | 70 | 77,609 | 3 | 0 | |
| Whatcom County | 185 | 263,552 | 0 | 1 | |
| Whitman County | 34 | 67,579 | 0 | 0 | |
| Yakima County | 222 | 271,851 | 0 | 0 |
under 30% 30 to 59% 60% and over
About this data
Share with violations counts any violation in the past three years, including monitoring and reporting lapses. Counts cover active systems; systems serving more than one county are counted in each.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Washington records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.