Public water system · CA4910018
ActiveArmstrong Valley-Cal Water Service (Puc)
At a glance
Armstrong Valley-Cal Water Service (Puc) (PWSID CA4910018) is an active community water system in Sonoma County, California. It reports serving 473 people through 280 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list one violation for this system; it is not health-based, and the most recent began in July 1993.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
473
Service connections
280
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Armstrong Valley-Cal Water Service (Puc) compare with other water systems in Sonoma County?
By EPA's size categories, Armstrong Valley-Cal Water Service (Puc) is a very small system (500 people or fewer). Sonoma County has 441 active public water systems. Its population served is about 57% below the county average of 1,092 people per system, and accounts for less than 0.1% of the 481,435 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 Armstrong Valley-Cal Water Service (Puc) 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 Armstrong Valley-Cal Water Service (Puc)?
EPA lists Armstrong Valley-Cal Water Service (Puc) 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. 371 of the 441 active systems in Sonoma County (84%) are also privately owned.
Does Armstrong Valley-Cal Water Service (Puc) have drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in July 1993. By type: 1 monitoring and reporting. The contaminant or rule involved is Lead and Copper Rule. EPA lists 1 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 |
|---|---|---|---|---|
| 1993-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
The one violation in EPA's records.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.
Armstrong Valley-Cal Water Service (Puc): frequently asked questions
Who runs Armstrong Valley-Cal Water Service (Puc)?
Armstrong Valley-Cal Water Service (Puc) (PWSID CA4910018) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Armstrong Valley-Cal Water Service (Puc) serve?
Armstrong Valley-Cal Water Service (Puc) reports serving 473 people through 280 service connections in Sonoma County, California.
Where does Armstrong Valley-Cal Water Service (Puc) 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 Armstrong Valley-Cal Water Service (Puc) have any drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in July 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 Armstrong Valley-Cal Water Service (Puc)'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 one violation for this system; it is not health-based, and the most recent began in July 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 Armstrong Valley-Cal Water Service (Puc)'s water quality report?
As a community water system, Armstrong Valley-Cal Water Service (Puc) 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 Sonoma County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Santa Rosa, City of | Sonoma | 175,396 | Community | Groundwater |
| Petaluma, City of | Sonoma | 60,781 | Community | Groundwater |
| Rohnert Park, City of | Sonoma | 43,821 | Community | Groundwater |
| Windsor, Town of | Sonoma | 25,561 | Community | Groundwater |
| Valley of the Moon Water District | Sonoma | 23,107 | Community | Groundwater |
| Sonoma, City of | Sonoma | 11,725 | 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, “Armstrong Valley-Cal Water Service (Puc), PWSID CA4910018, California”, https://aquacensus.com/water-systems/california/armstrong-valley-cal-water-service-puc-ca4910018 (data as of October 1, 2026).