Public water system · CA3610034
ActiveOntario Municipal Utilities Company
At a glance
Ontario Municipal Utilities Company (PWSID CA3610034) is an active community water system in San Bernardino County, California. It reports serving 185,010 people through 39,996 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list one violation for this system; it is health-based, and the most recent began in June 1993.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
185,010
Service connections
39,996
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Ontario Municipal Utilities Company compare with other water systems in San Bernardino County?
By EPA's size categories, Ontario Municipal Utilities Company is a very large system (more than 100,000 people). San Bernardino County has 306 active public water systems, and Ontario Municipal Utilities Company is the 4th-largest of them by population served. Its population served is about 20 times the county average of 9,227 people per system, and accounts for 6.6% of the 2,823,318 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 Ontario Municipal Utilities Company is about 28 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 Ontario Municipal Utilities Company?
EPA lists Ontario Municipal Utilities Company 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. 74 of the 306 active systems in San Bernardino County (24%) are also owned by a local government.
Does Ontario Municipal Utilities Company have drinking water violations?
EPA's records list one violation for this system; it is health-based, and the most recent began in June 1993. By type: 1 required treatment not met. The contaminant or rule involved is Surface Water Treatment Rule. 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 |
|---|---|---|---|---|
| 1993-06-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | 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.
Ontario Municipal Utilities Company: frequently asked questions
Who runs Ontario Municipal Utilities Company?
Ontario Municipal Utilities Company (PWSID CA3610034) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Ontario Municipal Utilities Company serve?
Ontario Municipal Utilities Company reports serving 185,010 people through 39,996 service connections in San Bernardino County, California.
Where does Ontario Municipal Utilities 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 Ontario Municipal Utilities Company have any drinking water violations?
EPA's records list one violation for this system; it is health-based, and the most recent began in June 1993. 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 Ontario Municipal Utilities 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. EPA's records list one violation for this system; it is health-based, and the most recent began in June 1993. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Ontario Municipal Utilities Company's water quality report?
As a community water system, Ontario Municipal Utilities 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 San Bernardino County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| San Gabriel Valley Wc - Fontana | San Bernardino | 237,700 | Community | Surface water |
| San Bernardino City | San Bernardino | 214,665 | Community | Groundwater |
| Cucamonga Valley Water District | San Bernardino | 211,069 | Community | Surface water |
| Victorville Water District | San Bernardino | 135,983 | Community | Purchased surface water |
| San Bernardino Valley Wd | San Bernardino | 109,608 | Community | Groundwater |
| East Valley Water District | San Bernardino | 108,629 | Community | Surface water |
Related pages
Working with water-system records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
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, “Ontario Municipal Utilities Company, PWSID CA3610034, California”, https://aquacensus.com/water-systems/california/ontario-municipal-utilities-company-ca3610034 (data as of October 1, 2026).