Public water system · CA3910012
ActiveCity of Stockton
At a glance
City of Stockton (PWSID CA3910012) is an active community water system in San Joaquin County, California. It reports serving 191,302 people through 51,522 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 9 violations for this system; 5 are health-based, and the most recent began in January 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
191,302
Service connections
51,522
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Stockton compare with other water systems in San Joaquin County?
By EPA's size categories, City of Stockton is a very large system (more than 100,000 people). San Joaquin County has 302 active public water systems, and City of Stockton is the largest of them by population served. Its population served is about 74 times the county average of 2,571 people per system, and accounts for 25% of the 776,334 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 Stockton is about 29 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 Stockton?
EPA lists City of Stockton 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. 69 of the 302 active systems in San Joaquin County (23%) are also owned by a local government.
Does City of Stockton have drinking water violations?
EPA's records list 9 violations for this system; 5 are health-based, and the most recent began in January 2024. The violations listed here began between December 1999 and January 2024. By type: 4 contaminant level above the legal limit, 2 monitoring and reporting, 2 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (3 of them). EPA lists 9 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 |
|---|---|---|---|---|
| 2024-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2023-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2023-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2021-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2016-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2013-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2005-11-01 | Public notice, recordkeeping or otherNotification, State · code 05 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2001-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 1999-12-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 9 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 Stockton: frequently asked questions
Who runs City of Stockton?
City of Stockton (PWSID CA3910012) 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 Stockton serve?
City of Stockton reports serving 191,302 people through 51,522 service connections in San Joaquin County, California.
Where does City of Stockton 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 Stockton have any drinking water violations?
EPA's records list 9 violations for this system; 5 are health-based, and the most recent began in January 2024. 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 Stockton'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 9 violations for this system; 5 are health-based, and the most recent began in January 2024. 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 Stockton's water quality report?
As a community water system, City of Stockton 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 San Joaquin County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| California Water Service - Stockton | San Joaquin | 176,266 | Community | Purchased surface water |
| Tracy, City of | San Joaquin | 96,609 | Community | Surface water |
| Manteca, City of | San Joaquin | 84,928 | Community | Purchased surface water |
| Lodi, City of | San Joaquin | 68,272 | Community | Surface water |
| City of Lathrop | San Joaquin | 35,080 | Community | Purchased surface water |
| City of Mountain House | San Joaquin | 24,948 | Community | 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 Stockton, PWSID CA3910012, California”, https://aquacensus.com/water-systems/california/city-of-stockton-ca3910012 (data as of October 1, 2026).