Washington Water Quality
Drinking water data for all 39 counties.
Avg Water Score
59.3
State Grade
D
Counties with Data
39
of 39 total
All Washington Counties
| County | Water Score |
|---|---|
| Asotin County | 86.0 |
| Columbia County | 86.0 |
| Douglas County | 86.0 |
| Jefferson County | 86.0 |
| Lincoln County | 86.0 |
| Pacific County | 86.0 |
| Pend Oreille County | 86.0 |
| Snohomish County | 86.0 |
| Wahkiakum County | 86.0 |
| Whitman County | 86.0 |
| King County | 71.1 |
| Clark County | 69.5 |
| Chelan County | 68.0 |
| Kitsap County | 67.5 |
| Cowlitz County | 66.4 |
| Kittitas County | 66.4 |
| Skagit County | 65.3 |
| Spokane County | 63.8 |
| Clallam County | 63.0 |
| Yakima County | 62.8 |
| Mason County | 62.2 |
| Adams County | 60.1 |
| Franklin County | 58.1 |
| Pierce County | 57.1 |
| Skamania County | 54.0 |
| Grays Harbor County | 53.6 |
| Klickitat County | 53.5 |
| Walla Walla County | 53.3 |
| Thurston County | 50.8 |
| Lewis County | 49.9 |
| Okanogan County | 49.7 |
| Whatcom County | 45.3 |
| Grant County | 42.5 |
| Benton County | 41.0 |
| Stevens County | 40.7 |
| Island County | 8.2 |
| San Juan County | 4.1 |
| Garfield County | 3.6 |
| Ferry County | 2.0 |
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Frequently Asked Questions
Which county in Washington has the best water quality?
Asotin County has the highest water quality score in Washington at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Washington has the most water violations?
Ferry County has among the lowest water quality scores in Washington at 2.0/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Washington?
Washington has an average water quality score of 59.3/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in Washington water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.
Data Source
Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.
Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.