Public water system · CA4000623
ActiveMutual Water Association
At a glance
Mutual Water Association (PWSID CA4000623) is an active non-transient non-community water system in San Luis Obispo County, California. It reports serving 30 people through 9 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 6 violations for this system; 1 is health-based, and the most recent began in October 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
30
Service connections
9
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Mutual Water Association compare with other water systems in San Luis Obispo County?
By EPA's size categories, Mutual Water Association 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 non-transient non-community water system reports serving 430 people, so Mutual Water Association is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. California has 1,466 active non-transient non-community water systems, 20% 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 Mutual Water Association?
EPA lists Mutual Water Association 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 Mutual Water Association have drinking water violations?
EPA's records list 6 violations for this system; 1 is health-based, and the most recent began in October 2024. The violations listed here began between October 1982 and October 2024. By type: 3 public notice, recordkeeping or other, 1 reporting, 1 required treatment not met and 1 monitoring and reporting. The contaminant or rule involved most often is Lead and Copper Rule Revisions (2 of them). EPA lists 3 as archived, 2 as unaddressed and 1 as resolved. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement. 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 |
|---|---|---|---|---|
| 2024-10-17 | ReportingLSL Reporting · code 4G | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2024-10-17 | Required treatment not metLSL Inventory · code 2E | Lead and Copper Rule Revisionscode 5200 | Yes | Unaddressed |
| 2022-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1982-12-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1982-11-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1982-10-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | 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.
Mutual Water Association: frequently asked questions
Who runs Mutual Water Association?
Mutual Water Association (PWSID CA4000623) is a non-transient non-community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Mutual Water Association serve?
Mutual Water Association reports serving 30 people through 9 service connections in San Luis Obispo County, California.
Where does Mutual Water Association 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 Mutual Water Association have any drinking water violations?
EPA's records list 6 violations for this system; 1 is health-based, and the most recent began in October 2024. 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 Mutual Water Association'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; 1 is health-based, and the most recent began in October 2024. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Mutual Water Association's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Mutual Water Association is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
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, “Mutual Water Association, PWSID CA4000623, California”, https://aquacensus.com/water-systems/california/mutual-water-association-ca4000623 (data as of October 1, 2026).