Public water system · CA0110001
ActiveAlameda County Water District
At a glance
Alameda County Water District (PWSID CA0110001) is an active community water system in Alameda County, California. It reports serving 344,000 people through 86,959 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in April 1996.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
344,000
Service connections
86,959
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Alameda County Water District compare with other water systems in Alameda County?
By EPA's size categories, Alameda County Water District is a very large system (more than 100,000 people). Alameda County has 27 active public water systems, and Alameda County Water District is the 2nd-largest of them by population served. Its population served is about 4.1 times the county average of 83,320 people per system, and accounts for 15% of the 2,249,634 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active community water system reports serving 6,703 people, so Alameda County Water District is about 51 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. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 609 California systems (8.1%) list surface water as their primary source.
Who owns and regulates Alameda County Water District?
EPA lists Alameda County Water District as owned by a local government. The CA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 15 of the 27 active systems in Alameda County (56%) are also owned by a local government.
Does Alameda County Water District have drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in April 1996. The violations listed here began between September 1992 and April 1996. By type: 1 contaminant level above the legal limit, 1 required treatment not met and 1 monitoring and reporting. The contaminant or rule involved most often is Total coliform bacteria (TCR) (2 of them). EPA lists 3 as resolved. 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 |
|---|---|---|---|---|
| 1996-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1993-06-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1992-09-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
All 3 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.
Alameda County Water District: frequently asked questions
Who runs Alameda County Water District?
Alameda County Water District (PWSID CA0110001) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Alameda County Water District serve?
Alameda County Water District reports serving 344,000 people through 86,959 service connections in Alameda County, California.
Where does Alameda County Water District 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 Alameda County Water District have any drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in April 1996. 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 Alameda County Water District'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 3 violations for this system; 2 are health-based, and the most recent began in April 1996. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Alameda County Water District's water quality report?
As a community water system, Alameda County Water District 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 Alameda County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| East Bay MUD | Alameda | 1,442,800 | Community | Surface water |
| City of Hayward | Alameda | 162,954 | Community | Purchased surface water |
| Dublin San Ramon Services District | Alameda | 98,776 | Community | Purchased surface water |
| City of Pleasanton | Alameda | 76,689 | Community | Purchased surface water |
| California Water Service - Livermore | Alameda | 60,414 | Community | Purchased surface water |
| City of Livermore | Alameda | 38,892 | Community | Purchased surface water |
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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, “Alameda County Water District, PWSID CA0110001, California”, https://aquacensus.com/water-systems/california/alameda-county-water-district-ca0110001 (data as of October 1, 2026).