Public water system · CA5500064
ActiveMuller Mutual Water Company
At a glance
Muller Mutual Water Company (PWSID CA5500064) is an active community water system in Tuolumne County, California. It reports serving 154 people through 55 service connections. Its primary water source is purchased surface water, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
154
Service connections
55
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Muller Mutual Water Company compare with other water systems in Tuolumne County?
By EPA's size categories, Muller Mutual Water Company is a very small system (500 people or fewer). Tuolumne County has 117 active public water systems. Its population served is well below the county average of 706 people per system, and accounts for 0.2% of the 82,611 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 Muller 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. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 506 California systems (6.8%) list purchased surface water as their primary source.
Who owns and regulates Muller Mutual Water Company?
EPA lists Muller 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. 75 of the 117 active systems in Tuolumne County (64%) are also privately owned.
Does Muller Mutual Water Company have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 2025. The violations listed here began between December 1983 and April 2025. By type: 10 public notice, recordkeeping or other, 1 monitoring and 1 monitoring and reporting. The contaminants or rules involved are Revised Total Coliform Rule and Lead and Copper Rule. EPA lists 10 as archived and 2 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. 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 |
|---|---|---|---|---|
| 2025-04-01 | MonitoringMonitoring, Lab Certification/Method Error (RTCR) · code 3D | Revised Total Coliform Rulecode 8000 | No | 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 |
| 1984-08-01 | 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 |
| 1984-06-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-05-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-04-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-03-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-02-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-01-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1983-12-01 | 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.
Muller Mutual Water Company: frequently asked questions
Who runs Muller Mutual Water Company?
Muller Mutual Water Company (PWSID CA5500064) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Muller Mutual Water Company serve?
Muller Mutual Water Company reports serving 154 people through 55 service connections in Tuolumne County, California.
Where does Muller Mutual Water Company get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Muller Mutual Water Company have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 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 Muller 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. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 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 Muller Mutual Water Company's water quality report?
As a community water system, Muller 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 Tuolumne County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Tud - Upper Basin Water System | Tuolumne | 13,280 | Community | Surface water |
| Tud - Sonora/Jamestown Water System | Tuolumne | 11,054 | Community | Surface water |
| Tud - Columbia Water System | Tuolumne | 5,463 | Community | Surface water |
| Peppery Bar and Grill, the | Tuolumne | 4,500 | Transient non-community | Groundwater |
| Cdcr - Sierra Conservation Center | Tuolumne | 3,571 | Community | Surface water |
| Groveland Community Serv Dist | Tuolumne | 3,400 | 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, “Muller Mutual Water Company, PWSID CA5500064, California”, https://aquacensus.com/water-systems/california/muller-mutual-water-company-ca5500064 (data as of October 1, 2026).