Public water system · CA4110020
ActivePalo Alto Park Mutual Water Company
At a glance
Palo Alto Park Mutual Water Company (PWSID CA4110020) is an active community water system in San Mateo County, California. It reports serving 2,900 people through 692 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 5 violations for this system; 1 is health-based, and the most recent began in June 2018.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,900
Service connections
692
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Palo Alto Park Mutual Water Company compare with other water systems in San Mateo County?
By EPA's size categories, Palo Alto Park Mutual Water Company is a small system (501 to 3,300 people). San Mateo County has 51 active public water systems. Its population served is well below the county average of 15,363 people per system, and accounts for 0.4% of the 783,522 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 Palo Alto Park Mutual Water Company is about 57% 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 Palo Alto Park Mutual Water Company?
EPA lists Palo Alto Park Mutual Water Company 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. 27 of the 51 active systems in San Mateo County (53%) are also privately owned.
Does Palo Alto Park Mutual Water Company have drinking water violations?
EPA's records list 5 violations for this system; 1 is health-based, and the most recent began in June 2018. The violations listed here began between August 1987 and June 2018. By type: 3 monitoring and reporting, 1 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) (2 of them). EPA lists 4 as resolved and 1 as archived. 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. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2018-06-14 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2015-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2001-07-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1993-06-30 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1987-08-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
All 5 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.
Palo Alto Park Mutual Water Company: frequently asked questions
Who runs Palo Alto Park Mutual Water Company?
Palo Alto Park Mutual Water Company (PWSID CA4110020) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Palo Alto Park Mutual Water Company serve?
Palo Alto Park Mutual Water Company reports serving 2,900 people through 692 service connections in San Mateo County, California.
Where does Palo Alto Park Mutual Water Company 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 Palo Alto Park Mutual Water Company have any drinking water violations?
EPA's records list 5 violations for this system; 1 is health-based, and the most recent began in June 2018. 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 Palo Alto Park Mutual Water 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 5 violations for this system; 1 is health-based, and the most recent began in June 2018. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Palo Alto Park Mutual Water Company's water quality report?
As a community water system, Palo Alto Park Mutual Water 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 Mateo County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Daly City | San Mateo | 104,901 | Community | Purchased surface water |
| California Water Service - San Mateo | San Mateo | 102,348 | Community | Purchased surface water |
| City of Redwood City | San Mateo | 92,819 | Community | Purchased surface water |
| California Water Service-S San Francisco | San Mateo | 64,146 | Community | Purchased surface water |
| California Water Service - Bear Gulch | San Mateo | 61,431 | Community | Surface water |
| City of San Bruno | San Mateo | 42,631 | 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, “Palo Alto Park Mutual Water Company, PWSID CA4110020, California”, https://aquacensus.com/water-systems/california/palo-alto-park-mutual-water-company-ca4110020 (data as of October 1, 2026).