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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
551–569 of 569Hamilton Water Department
WA5330700 · 540 served
Old Settlers Water Association
WA5363350 · 540 served
Sandy Hook Yacht Club Estates
WA5376050 · 540 served
Inchelium Water District
WA5335550 · 540 served
Madrona Beach Comm Water System
WA5349954 · 539 served
Stevens Co Pud - Spokane Lake Park
WA5383034 · 532 served
Burbank Irrigation District 4
WA5309300 · 527 served
Bethel Green Acres Water Assn
WA5305980 · 522 served
Town of Prescott
WA5369250 · 522 served
Great Basin Water Kiona
WA5310724 · 520 served
Rolling Firs Evergreen Terrace
WA5373975 · 514 served
Nespelem Water Dept
WA5359000 · 510 served
Kittitas County Water District #4
WA5342447 · 510 served
Stevens Co Pud - West Shore
WA5395450 · 505 served
Deming Water Assoc.
WA5318800 · 501 served
Home Valley Water District
WA5309188 · 500 served
Sunvista Sunlight Beach Hoa
WA5385160 · 500 served
Columbia View Water System
WA5314176 · 500 served
Mount Baker Water Association
WA5356500 · 500 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.
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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