Public water system · CA4310009
ActiveCity of Palo Alto
At a glance
City of Palo Alto (PWSID CA4310009) is an active community water system in Santa Clara County, California. It reports serving 67,231 people through 19,949 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 6 violations for this system; 5 are health-based, and the most recent began in March 2015.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
67,231
Service connections
19,949
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does City of Palo Alto compare with other water systems in Santa Clara County?
By EPA's size categories, City of Palo Alto is a large system (10,001 to 100,000 people). Santa Clara County has 121 active public water systems. Its population served is about 3.9 times the county average of 17,334 people per system, and accounts for 3.2% 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 Palo Alto is about 10 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 Palo Alto?
EPA lists City of Palo Alto 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 Palo Alto have drinking water violations?
EPA's records list 6 violations for this system; 5 are health-based, and the most recent began in March 2015. The violations listed here began between January 1992 and March 2015. By type: 3 required treatment not met, 2 contaminant level above the legal limit and 1 monitoring and reporting. The contaminant or rule involved most often is Surface Water Treatment Rule (3 of them). EPA lists 6 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 |
| 2012-05-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2010-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1995-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1992-03-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1992-01-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
All 6 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 Palo Alto: frequently asked questions
Who runs City of Palo Alto?
City of Palo Alto (PWSID CA4310009) 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 Palo Alto serve?
City of Palo Alto reports serving 67,231 people through 19,949 service connections in Santa Clara County, California.
Where does City of Palo Alto 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 Palo Alto have any drinking water violations?
EPA's records list 6 violations for this system; 5 are 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 Palo Alto'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 6 violations for this system; 5 are 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 Palo Alto's water quality report?
As a community water system, City of Palo Alto 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 |
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, “City of Palo Alto, PWSID CA4310009, California”, https://aquacensus.com/water-systems/california/city-of-palo-alto-ca4310009 (data as of October 1, 2026).