Public water system · CA4110022
ActiveCity of Redwood City
At a glance
City of Redwood City (PWSID CA4110022) is an active community water system in San Mateo County, California. It reports serving 92,819 people through 23,291 service connections. Its primary water source is purchased 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 March 2015.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
92,819
Service connections
23,291
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does City of Redwood City compare with other water systems in San Mateo County?
By EPA's size categories, City of Redwood City is a large system (10,001 to 100,000 people). San Mateo County has 51 active public water systems, and City of Redwood City is the 3rd-largest of them by population served. Its population served is about 6 times the county average of 15,363 people per system, and accounts for 12% of the 783,522 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 Redwood City is about 14 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. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 506 California systems (6.8%) list purchased surface water as their primary source.
Who owns and regulates City of Redwood City?
EPA lists City of Redwood City 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. 19 of the 51 active systems in San Mateo County (37%) are also owned by a local government.
Does City of Redwood City have drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in March 2015. The violations listed here began between April 2000 and March 2015. By type: 1 required treatment not met, 1 contaminant level above the legal limit 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 |
|---|---|---|---|---|
| 2015-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2014-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2000-04-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | 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.
City of Redwood City: frequently asked questions
Who runs City of Redwood City?
City of Redwood City (PWSID CA4110022) 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 Redwood City serve?
City of Redwood City reports serving 92,819 people through 23,291 service connections in San Mateo County, California.
Where does City of Redwood City get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does City of Redwood City have any drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in March 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 City of Redwood City'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 March 2015. 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 Redwood City's water quality report?
As a community water system, City of Redwood City 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 Mateo County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Daly City | San Mateo | 104,901 | Community | Purchased surface water |
| California Water Service - San Mateo | San Mateo | 102,348 | Community | Purchased surface water |
| California Water Service-S San Francisco | San Mateo | 64,146 | Community | Purchased surface water |
| California Water Service - Bear Gulch | San Mateo | 61,431 | Community | Surface water |
| City of San Bruno | San Mateo | 42,631 | Community | Purchased surface water |
| North Coast County Water Dist | San Mateo | 38,546 | 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 Redwood City, PWSID CA4110022, California”, https://aquacensus.com/water-systems/california/city-of-redwood-city-ca4110022 (data as of October 1, 2026).