Public water system · CA0710001
ActiveCity of Antioch
At a glance
City of Antioch (PWSID CA0710001) is an active community water system in Contra Costa County, California. It reports serving 115,074 people through 33,597 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; all are health-based, and the most recent began in January 1997.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
115,074
Service connections
33,597
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Antioch compare with other water systems in Contra Costa County?
By EPA's size categories, City of Antioch is a very large system (more than 100,000 people). Contra Costa County has 84 active public water systems, and City of Antioch is the 2nd-largest of them by population served. Its population served is about 17 times the county average of 6,726 people per system, and accounts for 20% of the 564,952 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 City of Antioch is about 17 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 City of Antioch?
EPA lists City of Antioch 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. 25 of the 84 active systems in Contra Costa County (30%) are also owned by a local government.
Does City of Antioch have drinking water violations?
EPA's records list 3 violations for this system; all are health-based, and the most recent began in January 1997. The violations listed here began between January 1992 and January 1997. By type: 2 contaminant level above the legal limit and 1 required treatment not met. 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 |
|---|---|---|---|---|
| 1997-01-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1992-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1992-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | 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.
City of Antioch: frequently asked questions
Who runs City of Antioch?
City of Antioch (PWSID CA0710001) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does City of Antioch serve?
City of Antioch reports serving 115,074 people through 33,597 service connections in Contra Costa County, California.
Where does City of Antioch 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 City of Antioch have any drinking water violations?
EPA's records list 3 violations for this system; all are health-based, and the most recent began in January 1997. 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 City of Antioch'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; all are health-based, and the most recent began in January 1997. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find City of Antioch's water quality report?
As a community water system, City of Antioch 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 Contra Costa County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Contra Costa Water District | Contra Costa | 198,000 | Community | Surface water |
| Brentwood | Contra Costa | 64,513 | Community | Purchased surface water |
| City of Pittsburg | Contra Costa | 62,500 | Community | Purchased surface water |
| Diablo Water District | Contra Costa | 43,357 | Community | Purchased surface water |
| City of Martinez | Contra Costa | 30,997 | Community | Purchased surface water |
| Golden State Water Company - Bay Point | Contra Costa | 23,731 | 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, “City of Antioch, PWSID CA0710001, California”, https://aquacensus.com/water-systems/california/city-of-antioch-ca0710001 (data as of October 1, 2026).