Public water system · CA4910017
ActiveWindsor, Town of
At a glance
Town of Windsor (PWSID CA4910017) is an active community water system in Sonoma County, California. It reports serving 25,561 people through 9,066 service connections. Its primary water source is groundwater, 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 January 2008.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
25,561
Service connections
9,066
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Town of Windsor compare with other water systems in Sonoma County?
By EPA's size categories, Town of Windsor is a large system (10,001 to 100,000 people). Sonoma County has 441 active public water systems, and Town of Windsor is the 4th-largest of them by population served. Its population served is about 23 times the county average of 1,092 people per system, and accounts for 5.3% of the 481,435 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 Town of Windsor is about 3.8 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. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 6,179 California systems (83%) list groundwater as their primary source.
Who owns and regulates Town of Windsor?
EPA lists Town of Windsor 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. 58 of the 441 active systems in Sonoma County (13%) are also owned by a local government.
Does Town of Windsor have drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in January 2008. The violations listed here began between July 2000 and January 2008. By type: 2 contaminant level above the legal limit and 1 public notice, recordkeeping or other. 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 |
|---|---|---|---|---|
| 2008-01-01 | Public notice, recordkeeping or otherOperations Report · code 10 | Not reported | No | Resolved |
| 2001-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2000-07-01 | 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.
Town of Windsor: frequently asked questions
Who runs Town of Windsor?
Town of Windsor (PWSID CA4910017) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Town of Windsor serve?
Town of Windsor reports serving 25,561 people through 9,066 service connections in Sonoma County, California.
Where does Town of Windsor 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 Town of Windsor have any drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in January 2008. 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 Town of Windsor'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 January 2008. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Town of Windsor's water quality report?
As a community water system, Town of Windsor 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 Sonoma County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Santa Rosa, City of | Sonoma | 175,396 | Community | Groundwater |
| Petaluma, City of | Sonoma | 60,781 | Community | Groundwater |
| Rohnert Park, City of | Sonoma | 43,821 | Community | Groundwater |
| Valley of the Moon Water District | Sonoma | 23,107 | Community | Groundwater |
| Sonoma, City of | Sonoma | 11,725 | Community | Groundwater |
| Sonoma State University | Sonoma | 10,986 | 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, “Windsor, Town of, PWSID CA4910017, California”, https://aquacensus.com/water-systems/california/windsor-town-of-ca4910017 (data as of October 1, 2026).