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
176–200 of 569Snoqualmie Pass Utility District
WA5381048 · 5,805 served
Benton City Water
WA5305800 · 5,626 served
Moxee Water Department
WA5357300 · 5,599 served
North Bainbridge Water Co
WA5359994 · 5,490 served
King County Water District #54
WA5339950 · 5,373 served
City of Mattawa
WA5352000 · 5,370 served
Westport Water Department
WA5395300 · 5,346 served
Wapato Waterworks
WA5392800 · 5,255 served
City of Deer Park
WA5318500 · 5,255 served
Point Evans
WA5368065 · 5,211 served
City of Connell
WA5314600 · 5,150 served
Grays Harbor Co Water Dist 2
WA5329250 · 5,112 served
Minterbrook
WA5354740 · 5,083 served
City of Medical Lake
WA5353400 · 4,982 served
Colville Water Department
WA5314200 · 4,945 served
City of Omak
WA5363750 · 4,940 served
Vinland
WA5391923 · 4,801 served
City of Warden
WA5392850 · 4,674 served
Pattison 500
WA5366578 · 4,643 served
Long Beach Water Department
WA5348000 · 4,628 served
Raymond Water Department
WA5371500 · 4,620 served
Belfair Water District 1
WA5305350 · 4,432 served
South Bainbridge
WA5381451 · 4,414 served
Castle Rock Municipal Water
WA5311800 · 4,367 served
Orchard Avenue Irrigation Dist 6
WA5364000 · 4,330 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
Quick Links
Data source: Utility data from EPA SDWIS. 569 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-18