Public water system · CA4000200
ActiveBassi Ranch Mutual Water Co.
At a glance
Bassi Ranch Mutual Water Co. (PWSID CA4000200) is an active community water system in San Luis Obispo County, California. It reports serving 85 people through 24 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
85
Service connections
24
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Bassi Ranch Mutual Water Co. compare with other water systems in San Luis Obispo County?
By EPA's size categories, Bassi Ranch Mutual Water Co. is a very small system (500 people or fewer). San Luis Obispo County has 171 active public water systems. Its population served is well below the county average of 2,038 people per system, and accounts for less than 0.1% of the 348,510 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 Bassi Ranch Mutual Water Co. 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 Bassi Ranch Mutual Water Co.?
EPA lists Bassi Ranch Mutual Water Co. 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. 130 of the 171 active systems in San Luis Obispo County (76%) are also privately owned.
Does Bassi Ranch Mutual Water Co. have drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2025. The violations listed here began between January 2018 and October 2025. By type: 6 monitoring and reporting. The contaminant or rule involved most often is Lead and Copper Rule (4 of them). EPA lists 5 as resolved and 1 as addressed. 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. Addressed means the violation is not resolved or archived and is covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Addressed |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2021-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2019-07-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2019-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2018-01-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
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.
Bassi Ranch Mutual Water Co.: frequently asked questions
Who runs Bassi Ranch Mutual Water Co.?
Bassi Ranch Mutual Water Co. (PWSID CA4000200) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Bassi Ranch Mutual Water Co. serve?
Bassi Ranch Mutual Water Co. reports serving 85 people through 24 service connections in San Luis Obispo County, California.
Where does Bassi Ranch Mutual Water Co. 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 Bassi Ranch Mutual Water Co. have any drinking water violations?
EPA's records list 6 violations for this system; none is health-based, and the most recent began in October 2025. 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 Bassi Ranch Mutual Water Co.'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; none is health-based, and the most recent began in October 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Bassi Ranch Mutual Water Co.'s water quality report?
As a community water system, Bassi Ranch Mutual Water Co. 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 Luis Obispo County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Santa Margarita Recreation Area | San Luis Obispo | 50,001 | Transient non-community | Groundwater |
| San Luis Obispo Water Department | San Luis Obispo | 47,788 | Community | Surface water |
| City of Paso Robles Water Division | San Luis Obispo | 31,176 | Community | Surface water |
| Atascadero Mutual Water Co | San Luis Obispo | 30,618 | Community | Groundwater |
| City of Arroyo Grande Utilities Division | San Luis Obispo | 17,963 | Community | Purchased surface water |
| California Mens Colony | San Luis Obispo | 15,000 | 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, “Bassi Ranch Mutual Water Co., PWSID CA4000200, California”, https://aquacensus.com/water-systems/california/bassi-ranch-mutual-water-co-ca4000200 (data as of October 1, 2026).