Public water system · CA1910169
ActiveWalnut Park Mutual Water Co.
At a glance
Walnut Park Mutual Water Co. (PWSID CA1910169) is an active community water system in Los Angeles County, California. It reports serving 16,180 people through 2,832 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in June 2023.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
16,180
Service connections
2,832
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Walnut Park Mutual Water Co. compare with other water systems in Los Angeles County?
By EPA's size categories, Walnut Park Mutual Water Co. is a large system (10,001 to 100,000 people). Los Angeles County has 275 active public water systems. Its population served is about 56% below the county average of 36,762 people per system, and accounts for 0.2% of the 10,109,668 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 Walnut Park Mutual Water Co. is about 141% above 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 Walnut Park Mutual Water Co.?
EPA lists Walnut Park 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. 150 of the 275 active systems in Los Angeles County (55%) are also privately owned.
Does Walnut Park Mutual Water Co. have drinking water violations?
EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in June 2023. The violations listed here began between January 1998 and June 2023. By type: 1 public notice, recordkeeping or other, 1 monitoring and reporting, 1 monitoring and 1 contaminant level above the legal limit. The contaminants or rules involved are Carbon tetrachloride, Lead and Copper Rule, Revised Total Coliform Rule and Total coliform bacteria (TCR). EPA lists 4 as resolved. 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 |
|---|---|---|---|---|
| 2023-06-01 | Public notice, recordkeeping or otherNotification, State · code 05 | Carbon tetrachloridecode 2982 | No | Resolved |
| 2019-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2016-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 1998-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 4 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.
Walnut Park Mutual Water Co.: frequently asked questions
Who runs Walnut Park Mutual Water Co.?
Walnut Park Mutual Water Co. (PWSID CA1910169) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Walnut Park Mutual Water Co. serve?
Walnut Park Mutual Water Co. reports serving 16,180 people through 2,832 service connections in Los Angeles County, California.
Where does Walnut Park 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 Walnut Park Mutual Water Co. have any drinking water violations?
EPA's records list 4 violations for this system; 1 is health-based, and the most recent began in June 2023. 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 Walnut Park 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 4 violations for this system; 1 is health-based, and the most recent began in June 2023. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Walnut Park Mutual Water Co.'s water quality report?
As a community water system, Walnut Park 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 Los Angeles County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Los Angeles-City, Dept. of Water & Power | Los Angeles | 3,875,566 | Community | Surface water |
| Long Beach Utilities Department | Los Angeles | 466,772 | Community | Purchased surface water |
| Santa Clarita Valley Water Agency | Los Angeles | 294,090 | Community | Surface water |
| Gswc - Southwest | Los Angeles | 277,740 | Community | Purchased surface water |
| San Gabriel Valley Water Co.-El Monte | Los Angeles | 248,000 | Community | Groundwater |
| Los Angeles Cwwd 40 Reg 4 & 34 Lancaster | Los Angeles | 208,129 | 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, “Walnut Park Mutual Water Co., PWSID CA1910169, California”, https://aquacensus.com/water-systems/california/walnut-park-mutual-water-co-ca1910169 (data as of October 1, 2026).