Public water system · CA3500825
ActiveUnion Heights Mwc
At a glance
Union Heights Mwc (PWSID CA3500825) is an active community water system in San Benito County, California. It reports serving 98 people through 29 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2009.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
98
Service connections
29
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Union Heights Mwc compare with other water systems in San Benito County?
By EPA's size categories, Union Heights Mwc is a very small system (500 people or fewer). San Benito County has 63 active public water systems. Its population served is well below the county average of 1,312 people per system, and accounts for 0.1% of the 82,670 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 Union Heights Mwc 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. 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 Union Heights Mwc?
EPA lists Union Heights Mwc 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. 46 of the 63 active systems in San Benito County (73%) are also privately owned.
Does Union Heights Mwc have drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2009. The violations listed here began between July 1999 and January 2009. By type: 7 monitoring and reporting, 4 contaminant level above the legal limit and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (5 of them). EPA lists 12 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 |
|---|---|---|---|---|
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2007-05-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2007-04-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2006-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2003-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2002-06-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2002-05-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1999-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Nitratecode 1040 | Yes | Resolved |
| 1999-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Nitratecode 1040 | Yes | Resolved |
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.
Union Heights Mwc: frequently asked questions
Who runs Union Heights Mwc?
Union Heights Mwc (PWSID CA3500825) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Union Heights Mwc serve?
Union Heights Mwc reports serving 98 people through 29 service connections in San Benito County, California.
Where does Union Heights Mwc 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 Union Heights Mwc have any drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in January 2009. 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 Union Heights Mwc'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, 4 are health-based, and the most recent began in January 2009. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Union Heights Mwc's water quality report?
As a community water system, Union Heights Mwc 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 Benito County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Hollister, City of | San Benito | 26,017 | Community | Purchased surface water |
| Sunnyslope County Water Dist | San Benito | 24,954 | Community | Purchased surface water |
| 33rd District Agricultural Association | San Benito | 9,000 | Transient non-community | Groundwater |
| San Benito High School | San Benito | 3,310 | Non-transient non-community | Groundwater |
| Aromas Water District | San Benito | 2,988 | Community | Groundwater |
| San Juan Bautista, City of | San Benito | 2,335 | Community | Groundwater |
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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, “Union Heights Mwc, PWSID CA3500825, California”, https://aquacensus.com/water-systems/california/union-heights-mwc-ca3500825 (data as of October 1, 2026).