State Hub
Washington Water Quality
569
Utilities in database
9.2M
Residents served
22%
On private wells
2
Key contaminants tracked
Drinking Water in Washington
Washington has 569 community water systems serving approximately 9.2 million residents. Primary water sources include groundwater. The most commonly reported contaminants include disinfection byproducts, lead. 22% of Washington residents rely on private wells. DOH holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in Washington
76–100 of 569City of Aberdeen
WA5300050 · 22,867 served
Pud #1 of Asotin County
WA5393343 · 21,930 served
King County Water District #125
WA5341998 · 21,904 served
Washington State University
WA5393200 · 21,506 served
City of Washougal
WA5393400 · 21,441 served
City of West Richland
WA5394900 · 21,231 served
Ridgefield Public Works
WA5372400 · 21,225 served
Consolidated Irrig Dist 19 System 2
WA5310221 · 21,220 served
Ellensburg Water Dept
WA5322950 · 20,900 served
City of Arlington
WA5302950 · 20,418 served
King County Water District No 90
WA5341150 · 20,100 served
Ferndale
WA5324850 · 19,305 served
Spo Co Water Dist 3 Sys 1
WA5393351 · 18,983 served
Modern Electric Water Co
WA5355600 · 18,487 served
City of Poulsbo
WA5369150 · 18,400 served
Lynden Water Department
WA5349150 · 17,969 served
City of Sunnyside
WA5385400 · 17,194 served
Eastern Washington University
WA5321900 · 17,108 served
City of Port Townsend
WA5369000 · 17,053 served
City of Cheney
WA5312400 · 16,954 served
Naval Base Kitsap at Bangor
WA5302714 · 16,828 served
City of Yelm
WA5399350 · 16,733 served
Naval Air Station/whidbey Island
WA5303420 · 16,595 served
Gig Harbor Water Dept
WA5327600 · 16,510 served
North Peninsula
WA5305122 · 16,449 served
Key Contaminant Concerns in Washington
Lead
Lead is a naturally occurring heavy metal that was widely used in plumbing infrastructure until it was banned for new installations in 1986. An estimated 9.2 million lead service lines still connect homes to public water mains across the United States, along with millions of homes with lead solder in their internal plumbing.
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
Washington Water FAQs
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Data source: Utility data from EPA SDWIS. 569 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-18