Public water system · WA5377050
ActiveSeattle Public Utilities
At a glance
Seattle Public Utilities (PWSID WA5377050) is an active community water system in King County, Washington. It reports serving 1,161,961 people through 195,204 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in December 2015.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
1,161,961
Service connections
195,204
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Seattle Public Utilities compare with other water systems in King County?
By EPA's size categories, Seattle Public Utilities is a very large system (more than 100,000 people). King County has 214 active public water systems, and Seattle Public Utilities is the largest of them by population served. Its population served is about 75 times the county average of 15,523 people per system, and accounts for 35% 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 Seattle Public Utilities is about 173 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. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 140 Washington systems (3%) list surface water as their primary source.
Who owns and regulates Seattle Public Utilities?
EPA lists Seattle Public Utilities 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 Seattle Public Utilities have drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in December 2015. The violations listed here began between October 1979 and December 2015. By type: 3 monitoring and reporting and 2 required treatment not met. The contaminant or rule involved most often is Nitrate (2 of them). EPA lists 3 as resolved and 2 as archived. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. 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 |
|---|---|---|---|---|
| 2015-12-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2007-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2007-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1995-01-01 | Required treatment not metOCCT/SOWT Treatment Installation/Demonstration · code 58 | Lead and Copper Rulecode 5000 | Yes | Archived |
| 1979-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 5 violations in EPA's records, newest first.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.
Seattle Public Utilities: frequently asked questions
Who runs Seattle Public Utilities?
Seattle Public Utilities (PWSID WA5377050) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does Seattle Public Utilities serve?
Seattle Public Utilities reports serving 1,161,961 people through 195,204 service connections in King County, Washington.
Where does Seattle Public Utilities get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Seattle Public Utilities have any drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in December 2015. 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 Seattle Public Utilities' 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 5 violations for this system; 2 are health-based, and the most recent began in December 2015. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.
Where can I find Seattle Public Utilities' water quality report?
As a community water system, Seattle Public Utilities 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 |
|---|---|---|---|---|
| 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 |
| Auburn City of | King | 107,655 | Community | Groundwater |
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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, “Seattle Public Utilities, PWSID WA5377050, Washington”, https://aquacensus.com/water-systems/washington/seattle-public-utilities-wa5377050 (data as of October 1, 2026).