Public water system · CA1910155
ActiveGswc - Southwest
At a glance
Gswc - Southwest (PWSID CA1910155) is an active community water system in Los Angeles County, California. It reports serving 277,740 people through 52,644 service connections. Its primary water source is purchased surface water, and EPA lists it as privately owned. EPA's records list 3 violations for this system; 1 is health-based, and the most recent began in November 2014.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
277,740
Service connections
52,644
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Gswc - Southwest compare with other water systems in Los Angeles County?
By EPA's size categories, Gswc - Southwest is a very large system (more than 100,000 people). Los Angeles County has 275 active public water systems, and Gswc - Southwest is the 4th-largest of them by population served. Its population served is about 7.6 times the county average of 36,762 people per system, and accounts for 2.7% 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 Gswc - Southwest is about 41 times 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 Gswc - Southwest?
EPA lists Gswc - Southwest 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 Gswc - Southwest have drinking water violations?
EPA's records list 3 violations for this system; 1 is health-based, and the most recent began in November 2014. The violations listed here began between June 2007 and November 2014. By type: 2 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (2 of them). EPA lists 3 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 |
|---|---|---|---|---|
| 2014-11-21 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2011-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2007-06-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
All 3 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.
Gswc - Southwest: frequently asked questions
Who runs Gswc - Southwest?
Gswc - Southwest (PWSID CA1910155) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Gswc - Southwest serve?
Gswc - Southwest reports serving 277,740 people through 52,644 service connections in Los Angeles County, California.
Where does Gswc - Southwest 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 Gswc - Southwest have any drinking water violations?
EPA's records list 3 violations for this system; 1 is health-based, and the most recent began in November 2014. 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 Gswc - Southwest'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 3 violations for this system; 1 is health-based, and the most recent began in November 2014. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Gswc - Southwest's water quality report?
As a community water system, Gswc - Southwest 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 |
| 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 |
| Glendale-City, Water Dept. | Los Angeles | 188,784 | 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, “Gswc - Southwest, PWSID CA1910155, California”, https://aquacensus.com/water-systems/california/gswc-southwest-ca1910155 (data as of October 1, 2026).