Public water system · WA5307220
ActiveBlack Diamond Water Dept
At a glance
Black Diamond Water Dept (PWSID WA5307220) is an active community water system in King County, Washington. It reports serving 6,407 people through 2,368 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2017.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
6,407
Service connections
2,368
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Black Diamond Water Dept compare with other water systems in King County?
By EPA's size categories, Black Diamond Water Dept is a medium system (3,301 to 10,000 people). King County has 214 active public water systems. Its population served is about 59% below the county average of 15,523 people per system, and accounts for 0.2% 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 Black Diamond Water Dept is roughly in line with 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. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 4,370 Washington systems (93%) list groundwater as their primary source.
Who owns and regulates Black Diamond Water Dept?
EPA lists Black Diamond Water Dept 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 Black Diamond Water Dept have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2017. The violations listed here began between April 2008 and July 2017. By type: 10 monitoring and reporting and 2 public notice, recordkeeping or other. The contaminant or rule involved most often is Consumer Confidence Rule (2 of them). EPA lists 10 as archived and 2 as resolved. 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. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2017-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2016-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloropropanecode 2983 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Hexachlorobenzenecode 2274 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Picloramcode 2040 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Trichloroethylenecode 2984 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Alachlor (Lasso)code 2051 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Pentachlorophenolcode 2326 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,1-Trichloroethanecode 2981 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Atrazinecode 2050 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbon tetrachloridecode 2982 | No | Archived |
| 2008-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Archived |
The 12 most recent 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.
Black Diamond Water Dept: frequently asked questions
Who runs Black Diamond Water Dept?
Black Diamond Water Dept (PWSID WA5307220) is a community water system owned by a local government. It is regulated by the WA state drinking water program.
How many people does Black Diamond Water Dept serve?
Black Diamond Water Dept reports serving 6,407 people through 2,368 service connections in King County, Washington.
Where does Black Diamond Water Dept get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Black Diamond Water Dept have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2017. 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 Black Diamond Water Dept'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. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2017. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.
Where can I find Black Diamond Water Dept's water quality report?
As a community water system, Black Diamond Water Dept 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 |
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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, “Black Diamond Water Dept, PWSID WA5307220, Washington”, https://aquacensus.com/water-systems/washington/black-diamond-water-dept-wa5307220 (data as of October 1, 2026).