Public water system · WA5338950
ActiveKing County Water District #20
At a glance
King County Water District #20 (PWSID WA5338950) is an active community water system in King County, Washington. It reports serving 48,469 people through 14,783 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list one violation for this system; it is health-based, and the most recent began in July 2003.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
48,469
Service connections
14,783
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does King County Water District #20 compare with other water systems in King County?
By EPA's size categories, King County Water District #20 is a large system (10,001 to 100,000 people). King County has 214 active public water systems. Its population served is about 3.1 times the county average of 15,523 people per system, and accounts for 1.5% of the 3,321,960 people reported by systems filed under the county. Across Washington, the 4,705 active systems average 2,172 people each. Nationally, the average active community water system reports serving 6,703 people, so King County Water District #20 is about 7.2 times that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Washington has 2,392 active community water systems, 51% of the state's 4,705 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 130 Washington systems (2.8%) list purchased surface water as their primary source.
Who owns and regulates King County Water District #20?
EPA lists King County Water District #20 as owned by a local government. The WA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 58 of the 214 active systems in King County (27%) are also owned by a local government.
Does King County Water District #20 have drinking water violations?
EPA's records list one violation for this system; it is health-based, and the most recent began in July 2003. By type: 1 contaminant level above the legal limit. The contaminant or rule involved is Total coliform bacteria (TCR). EPA lists 1 as archived. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2003-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
The one violation in EPA's records.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
King County Water District #20: frequently asked questions
Who runs King County Water District #20?
King County Water District #20 (PWSID WA5338950) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does King County Water District #20 serve?
King County Water District #20 reports serving 48,469 people through 14,783 service connections in King County, Washington.
Where does King County Water District #20 get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does King County Water District #20 have any drinking water violations?
EPA's records list one violation for this system; it is health-based, and the most recent began in July 2003. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is King County Water District #20's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list one violation for this system; it is health-based, and the most recent began in July 2003. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.
Where can I find King County Water District #20's water quality report?
As a community water system, King County Water District #20 must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in King County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Seattle Public Utilities | King | 1,161,961 | Community | Surface water |
| Bellevue City of | King | 321,349 | Community | Purchased surface water |
| Kent Water Department | King | 166,421 | Community | Purchased surface water |
| Redmond Water System City of | King | 163,335 | Community | Purchased surface water |
| Lakehaven Water and Sewer District | King | 148,809 | Community | Purchased surface water |
| Renton City of | King | 108,091 | Community | Groundwater |
Related pages
Working with water-system records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “King County Water District #20, PWSID WA5338950, Washington”, https://aquacensus.com/water-systems/washington/king-county-water-district-20-wa5338950 (data as of October 1, 2026).