Public water system · CA4310014

Active

City of Sunnyvale

At a glance

City of Sunnyvale (PWSID CA4310014) is an active community water system in Santa Clara County, California. It reports serving 157,566 people through 28,372 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in March 2015.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO public records.

Population served

157,566

Service connections

28,372

Primary source

SWP

Purchased surface water

System type

CWS

Community water system

System record

PWSIDCA4310014

System typeCommunity water system

Activity statusActive

Population served157,566

Service connections28,372

Primary water sourcePurchased surface water

Owner typeLocal government

Primacy agencyCA state drinking water program

City servedSunnyvale

StateCalifornia

ZIP—

CountySanta Clara County

How does City of Sunnyvale compare with other water systems in Santa Clara County?

By EPA's size categories, City of Sunnyvale is a very large system (more than 100,000 people). Santa Clara County has 121 active public water systems, and City of Sunnyvale is the 2nd-largest of them by population served. Its population served is about 9.1 times the county average of 17,334 people per system, and accounts for 7.5% 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 Sunnyvale is about 24 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 City of Sunnyvale?

EPA lists City of Sunnyvale 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 Sunnyvale have drinking water violations?

Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in March 2015. The violations listed here began between January 2015 and March 2015. By type: 11 monitoring and reporting and 1 required treatment not met. The contaminants or rules involved are Surface Water Treatment Rule, Toxaphene, Diquat and 1,1-Dichloroethylene. 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
2015-03-01	Required treatment not metTreatment Technique (SWTR and GWR) · code 41	Surface Water Treatment Rulecode 0200	Yes	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Toxaphenecode 2020	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Diquatcode 2032	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	1,1-Dichloroethylenecode 2977	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Oxamylcode 2036	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Nickelcode 1036	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	p-Dichlorobenzenecode 2969	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Berylliumcode 1075	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Vinyl chloridecode 2976	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Chlordanecode 2959	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Antimonycode 1074	No	Resolved
2015-01-01	Monitoring and reportingMonitoring, Regular · code 03	Seleniumcode 1045	No	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.

City of Sunnyvale: frequently asked questions

Who runs City of Sunnyvale?

City of Sunnyvale (PWSID CA4310014) 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 Sunnyvale serve?

City of Sunnyvale reports serving 157,566 people through 28,372 service connections in Santa Clara County, California.

Where does City of Sunnyvale 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 Sunnyvale have any drinking water violations?

Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in March 2015. 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 Sunnyvale'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, one is health-based, and the most recent began in March 2015. 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 Sunnyvale's water quality report?

As a community water system, City of Sunnyvale 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 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
City of Mountain View	Santa Clara	81,501	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 Sunnyvale, PWSID CA4310014, California”, https://aquacensus.com/water-systems/california/city-of-sunnyvale-ca4310014 (data as of October 1, 2026).