Public water system · CA4900536
ActiveOccidental Community Services District
At a glance
Occidental Community Services District (PWSID CA4900536) is an active community water system in Sonoma County, California. It reports serving 533 people through 110 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2018.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
533
Service connections
110
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Occidental Community Services District compare with other water systems in Sonoma County?
By EPA's size categories, Occidental Community Services District is a small system (501 to 3,300 people). Sonoma County has 441 active public water systems. Its population served is about half of the county average of 1,092 people per system, and accounts for 0.1% 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 Occidental Community Services District is well below 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 Occidental Community Services District?
EPA lists Occidental Community Services 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. 58 of the 441 active systems in Sonoma County (13%) are also owned by a local government.
Does Occidental Community Services District have drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2018. The violations listed here began between July 1984 and September 2018. By type: 5 monitoring and reporting, 3 public notice, recordkeeping or other, 2 required treatment not met, 1 monitoring and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Surface Water Treatment Rule (3 of them). EPA lists 10 as resolved and 2 as archived. 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. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2018-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2014-07-01 | Public notice, recordkeeping or otherVariance/Exemption/Other Compliance · code 08 | Not reported | No | Resolved |
| 2005-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2005-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2003-09-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2001-01-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1999-07-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 1995-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1995-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1993-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1984-09-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-07-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
The 12 most recent 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.
Occidental Community Services District: frequently asked questions
Who runs Occidental Community Services District?
Occidental Community Services District (PWSID CA4900536) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Occidental Community Services District serve?
Occidental Community Services District reports serving 533 people through 110 service connections in Sonoma County, California.
Where does Occidental Community Services District 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 Occidental Community Services District have any drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2018. 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 Occidental Community Services 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. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in September 2018. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Occidental Community Services District's water quality report?
As a community water system, Occidental Community Services 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 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 |
| Windsor, Town of | Sonoma | 25,561 | Community | Groundwater |
| Valley of the Moon Water District | Sonoma | 23,107 | Community | Groundwater |
| Sonoma, City of | Sonoma | 11,725 | 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, “Occidental Community Services District, PWSID CA4900536, California”, https://aquacensus.com/water-systems/california/occidental-community-services-district-ca4900536 (data as of October 1, 2026).