Public water system · CA1910090
ActiveMonrovia-City, Water Dept.
At a glance
Monrovia-City, Water Dept. (PWSID CA1910090) is an active community water system in Los Angeles County, California. It reports serving 37,931 people through 9,597 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list one violation for this system; it is not health-based, and the most recent began in May 2023.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
37,931
Service connections
9,597
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Monrovia-City, Water Dept. compare with other water systems in Los Angeles County?
By EPA's size categories, Monrovia-City, Water Dept. is a large system (10,001 to 100,000 people). Los Angeles County has 275 active public water systems. Its population served is roughly in line with the county average of 36,762 people per system, and accounts for 0.4% 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 Monrovia-City, Water Dept. is about 5.7 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. 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 Monrovia-City, Water Dept.?
EPA lists Monrovia-City, Water Dept. as owned by a local government. 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. 100 of the 275 active systems in Los Angeles County (36%) are also owned by a local government.
Does Monrovia-City, Water Dept. have drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in May 2023. By type: 1 monitoring and reporting. The contaminant or rule involved is Nitrate. EPA lists 1 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 |
|---|---|---|---|---|
| 2023-05-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
The one violation in EPA's records.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.
Monrovia-City, Water Dept.: frequently asked questions
Who runs Monrovia-City, Water Dept.?
Monrovia-City, Water Dept. (PWSID CA1910090) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Monrovia-City, Water Dept. serve?
Monrovia-City, Water Dept. reports serving 37,931 people through 9,597 service connections in Los Angeles County, California.
Where does Monrovia-City, Water Dept. 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 Monrovia-City, Water Dept. have any drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in May 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 Monrovia-City, Water Dept.'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 one violation for this system; it is not health-based, and the most recent began in May 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 Monrovia-City, Water Dept.'s water quality report?
As a community water system, Monrovia-City, Water Dept. 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, “Monrovia-City, Water Dept., PWSID CA1910090, California”, https://aquacensus.com/water-systems/california/monrovia-city-water-dept-ca1910090 (data as of October 1, 2026).