Public water system · CA4310018
ActiveCity of Cupertino
At a glance
City of Cupertino (PWSID CA4310018) is an active community water system in Santa Clara County, California. It reports serving 16,336 people through 4,692 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 3 violations for this system; all are health-based, and the most recent began in February 1993.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
16,336
Service connections
4,692
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does City of Cupertino compare with other water systems in Santa Clara County?
By EPA's size categories, City of Cupertino is a large system (10,001 to 100,000 people). Santa Clara County has 121 active public water systems. Its population served is roughly in line with the county average of 17,334 people per system, and accounts for 0.8% of the 2,097,447 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 City of Cupertino is about 144% 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. 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 City of Cupertino?
EPA lists City of Cupertino 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. 34 of the 121 active systems in Santa Clara County (28%) are also owned by a local government.
Does City of Cupertino have drinking water violations?
EPA's records list 3 violations for this system; all are health-based, and the most recent began in February 1993. The violations listed here began between September 1992 and February 1993. By type: 3 contaminant level above the legal limit. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (3 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 |
|---|---|---|---|---|
| 1993-02-22 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 1992-11-24 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | 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.
City of Cupertino: frequently asked questions
Who runs City of Cupertino?
City of Cupertino (PWSID CA4310018) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does City of Cupertino serve?
City of Cupertino reports serving 16,336 people through 4,692 service connections in Santa Clara County, California.
Where does City of Cupertino 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 City of Cupertino have any drinking water violations?
EPA's records list 3 violations for this system; all are health-based, and the most recent began in February 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 City of Cupertino'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; all are health-based, and the most recent began in February 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 City of Cupertino's water quality report?
As a community water system, City of Cupertino 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 Santa Clara County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| San Jose Water | Santa Clara | 1,039,920 | Community | Surface water |
| City of Sunnyvale | Santa Clara | 157,566 | Community | Purchased surface water |
| City of Santa Clara | Santa Clara | 130,746 | Community | Purchased surface water |
| Great Oaks Wc Inc. | Santa Clara | 110,088 | Community | Groundwater |
| City of San Jose - Evg/Edv/Coy | Santa Clara | 101,265 | Community | Purchased surface water |
| City of Milpitas | Santa Clara | 81,773 | 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, “City of Cupertino, PWSID CA4310018, California”, https://aquacensus.com/water-systems/california/city-of-cupertino-ca4310018 (data as of October 1, 2026).