Public water system · CA4200580
ActiveSan Marcos Mutual Water Company
At a glance
San Marcos Mutual Water Company (PWSID CA4200580) is an active community water system in Santa Barbara County, California. It reports serving 120 people through 38 service connections. Its primary water source is groundwater under influence of surface water, and EPA lists it as privately owned. EPA's records list 6 violations for this system; 4 are health-based, and the most recent began in September 2004.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
120
Service connections
38
Primary source
GU
Groundwater under influence of surface water
System type
CWS
Community water system
System record
How does San Marcos Mutual Water Company compare with other water systems in Santa Barbara County?
By EPA's size categories, San Marcos Mutual Water Company is a very small system (500 people or fewer). Santa Barbara County has 150 active public water systems. Its population served is well below the county average of 3,255 people per system, and accounts for less than 0.1% of the 488,317 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 San Marcos Mutual Water Company 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 under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules. 105 California systems (1.4%) list groundwater under influence of surface water as their primary source.
Who owns and regulates San Marcos Mutual Water Company?
EPA lists San Marcos Mutual Water Company as privately owned. 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. 121 of the 150 active systems in Santa Barbara County (81%) are also privately owned.
Does San Marcos Mutual Water Company have drinking water violations?
EPA's records list 6 violations for this system; 4 are health-based, and the most recent began in September 2004. The violations listed here began between October 1980 and September 2004. By type: 4 contaminant level above the legal limit and 2 monitoring and reporting. The contaminant or rule involved most often is Total coliform bacteria (TCR) (4 of them). EPA lists 4 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 |
|---|---|---|---|---|
| 2004-09-01 | 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 |
| 1997-03-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1996-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1981-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
| 1980-10-30 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 6 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.
San Marcos Mutual Water Company: frequently asked questions
Who runs San Marcos Mutual Water Company?
San Marcos Mutual Water Company (PWSID CA4200580) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does San Marcos Mutual Water Company serve?
San Marcos Mutual Water Company reports serving 120 people through 38 service connections in Santa Barbara County, California.
Where does San Marcos Mutual Water Company get its water?
EPA SDWIS lists this system's primary water source as groundwater under influence of surface water. Groundwater under the influence of surface water is well or spring water that the regulator has found to be affected by nearby surface water, so it is regulated under the surface-water treatment rules.
Does San Marcos Mutual Water Company have any drinking water violations?
EPA's records list 6 violations for this system; 4 are health-based, and the most recent began in September 2004. 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 San Marcos Mutual Water Company'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 6 violations for this system; 4 are health-based, and the most recent began in September 2004. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find San Marcos Mutual Water Company's water quality report?
As a community water system, San Marcos Mutual Water Company 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 Santa Barbara County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Santa Maria Utilities Department | Santa Barbara | 109,477 | Community | Purchased surface water |
| City of Santa Barbara Water Department | Santa Barbara | 99,323 | Community | Surface water |
| Goleta Water District | Santa Barbara | 84,462 | Community | Surface water |
| Lompoc-City Water Utility Div | Santa Barbara | 40,473 | Community | Surface water |
| Golden State Water Company - Orcutt | Santa Barbara | 34,102 | Community | Purchased surface water |
| Carpinteria Valley Water District | Santa Barbara | 15,996 | 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, “San Marcos Mutual Water Company, PWSID CA4200580, California”, https://aquacensus.com/water-systems/california/san-marcos-mutual-water-company-ca4200580 (data as of October 1, 2026).