States → Washington
State profile · EPA SDWIS + UCMR5
Washington Drinking Water Quality
4,557 public water systems serve 9,736,844 people across Washington, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 4,557
- Water systems
- 314,648
- Total violations
- 92.1%
- Systems w/ a violation
- 39.7%
- PFAS detection rate
The verdict
Across Washington, 4,199 of 4,557 water systems (92.1%) carry at least one EPA violation, and 98 of 247 UCMR5-tested systems show PFAS.
- 314,648
- Total EPA violations on record
- 7%
- Health-based (MCL / treatment)
- 92.1%
- Systems with ≥1 violation
- 39.7%
- UCMR5 PFAS detection rate
Water Systems
4,557
Total Violations
314,648
Violation Rate
92.1%
PFAS Detection
39.7%
98 of 247 tested
Violation Composition
How Washington's 314,648 violations break down by type, per EPA SDWIS classification.
Health-based (20,590) Monitoring/Reporting (294,058)
| Metric | Value | Share |
|---|---|---|
| Public water systems | 4,557 | - |
| Population served | 9,736,844 | - |
| Total violations | 314,648 | 100% |
| Health-based violations | 20,590 | 6.5% |
| Systems with violations | 4,199 | 92.1% |
| PFAS detection rate | 98 of 247 | 39.7% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Seattle Public Utilities
Seattle, WA · 1,091,904 served
Tacoma Water Division City Of
Tacoma, WA · 448,771 served
Vancouver City Of
Vancouver, WA · 373,047 served
Spokane City Of
Spokane, WA · 343,167 served
Bellevue City Of
Bellevue, WA · 317,330 served
Everett Public Works Dept. City Of
Everett, WA · 215,774 served
Alderwood Water District
Lynnwood, WA · 200,000 served
Kent Water Department
Kent, WA · 166,421 served
Redmond Water System City Of
Redmond, WA · 163,335 served
Bellingham-Water Division City Of
Bellingham, WA · 139,912 served
Lakehaven Water and Sewer District
Federal Way, WA · 118,273 served
Clark Public Utilities
Vancouver, WA · 116,876 served
Pasco Water Department
Pasco, WA · 116,342 served
Highline Water District
Kent, WA · 115,950 served
Kennewick City Of
Kennewick, WA · 114,468 served
Olympia City Of
Olympia, WA · 113,584 served
Auburn City of
Auburn, WA · 113,095 served
Yakima Water Division City Of
Yakima, WA · 112,858 served
Skagit County PUD 1 Judy Res
Mount Vernon, WA · 111,415 served
Renton City Of
Renton, WA · 107,119 served
Most Violations
#1 Lake Forest Park Water District Lake Forest Park
9,527 #2 Satsop Business Park Aberdeen
5,255 #3 Marble Water System Northport
4,269 #4 Kelley Crest Woodland
4,066 #5 Dabob Cove Community Quilcene
3,893 #6 Vista del Rio Mobile Home Park Vancouver
3,450 #7 Lewis River Golf Course Kelso
3,259 #8 Tempo Lake Water Co Port Orchard
3,044 #9 Tel Company 3 Freeland
2,633 #10 Taggares Fruit Co Burbank
2,455 #11 Lewis Co Water Dist #2 Onalaska
2,344 #12 Pioneer Olympia
2,002 #13 Ostrom Mushroom Farms Port Orchard
1,825 #14 Roche Harbor Water System Inc Friday Harbor
1,788 #15 Woodland Park Mobil Court Yakima
1,788 Counties in Washington
King
217 systems · 3,193,095 served
· 20,636 violations
Pierce
359 systems · 1,138,508 served
· 14,826 violations
Snohomish
170 systems · 947,238 served
· 8,193 violations
Spokane
164 systems · 621,798 served
· 9,829 violations
Clark
72 systems · 615,931 served
· 9,864 violations
Thurston
322 systems · 395,780 served
· 24,330 violations
Kitsap
221 systems · 331,366 served
· 12,667 violations
Benton
113 systems · 281,453 served
· 10,713 violations
Yakima
220 systems · 268,022 served
· 12,104 violations
Whatcom
185 systems · 258,702 served
· 11,873 violations
Skagit
87 systems · 156,499 served
· 2,324 violations
Grant
268 systems · 145,560 served
· 12,635 violations
Franklin
79 systems · 132,513 served
· 3,941 violations
Chelan
132 systems · 118,807 served
· 4,357 violations
Cowlitz
76 systems · 115,789 served
· 13,735 violations
Island
308 systems · 104,049 served
· 25,141 violations
Clallam
101 systems · 91,937 served
· 6,174 violations
Lewis
166 systems · 88,839 served
· 15,450 violations
Grays Harbor
88 systems · 83,246 served
· 13,309 violations
Mason
241 systems · 78,167 served
· 10,829 violations
Walla Walla
69 systems · 75,527 served
· 8,476 violations
Whitman
33 systems · 65,902 served
· 1,462 violations
Kittitas
104 systems · 51,670 served
· 3,250 violations
Jefferson
70 systems · 46,719 served
· 8,616 violations
Okanogan
123 systems · 44,103 served
· 7,257 violations
Douglas
46 systems · 40,088 served
· 3,795 violations
San Juan
112 systems · 39,901 served
· 6,963 violations
Stevens
68 systems · 33,702 served
· 10,726 violations
Pacific
38 systems · 33,692 served
· 3,844 violations
Adams
48 systems · 25,650 served
· 3,951 violations
Showing top 30 of 39 counties.
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Washington? ▼
Washington has 4,557 public water systems serving approximately 9,736,844 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in Washington? ▼
Washington has 314,648 total drinking water violations on record, with 20,590 classified as health-based violations. 92.1% of water systems in the state have at least one violation.
Has PFAS been found in Washington drinking water? ▼
Of 247 water systems tested for PFAS in Washington, 98 had PFAS detected, a 39.7% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for Washington water systems? ▼
Washington's violation rate is 92.1%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this Washington water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.