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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
Top 20 of 569 by populationSeattle Public Utilities
WA5377050 · 1,161,961 served
City of Tacoma Water Division
WA5386800 · 446,170 served
City of Vancouver
WA5391200 · 373,047 served
City of Spokane
WA5383100 · 343,167 served
City of Bellevue
WA5305575 · 321,349 served
Alderwood Water District
WA5301300 · 245,715 served
City of Everett Public Works Dept.
WA5324050 · 215,774 served
Kent Water Department
WA5338150 · 166,421 served
City of Redmond Water System
WA5371650 · 163,335 served
Clark Public Utilities
WA5313333 · 153,526 served
Lakehaven Water and Sewer District
WA5341997 · 148,809 served
City of Bellingham-water Division
WA5305600 · 141,127 served
City of Olympia
WA5363450 · 126,966 served
City of Kennewick
WA5338100 · 118,164 served
Pasco Water Department
WA5366400 · 115,102 served
City of Yakima Water Division
WA5399150 · 112,858 served
Skagit County Pud 1 Judy Res
WA5379500 · 111,415 served
City of Renton
WA5371850 · 108,091 served
City of Auburn
WA5303350 · 107,655 served
City of Richland
WA5372250 · 106,499 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