Public water system · CA2800555
ActiveTwomey Cellars
At a glance
Twomey Cellars (PWSID CA2800555) is an active transient non-community water system in Napa County, California. It reports serving 43 people through 1 service connection. Its primary water source is groundwater, and EPA lists it as privately owned. EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in July 2022.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
43
Service connections
1
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Twomey Cellars compare with other water systems in Napa County?
By EPA's size categories, Twomey Cellars is a very small system (500 people or fewer). Napa County has 188 active public water systems. Its population served is well below the county average of 861 people per system, and accounts for less than 0.1% of the 161,950 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Twomey Cellars is well below that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. California has 3,016 active transient non-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 Twomey Cellars?
EPA lists Twomey Cellars 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. 168 of the 188 active systems in Napa County (89%) are also privately owned.
Does Twomey Cellars have drinking water violations?
EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in July 2022. The violations listed here began between July 1998 and July 2022. By type: 6 monitoring and reporting, 1 monitoring and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (7 of them). EPA lists 7 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 |
|---|---|---|---|---|
| 2022-07-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2009-04-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2003-10-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2002-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2001-07-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2001-04-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1999-07-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1998-07-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Archived |
All 8 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.
Twomey Cellars: frequently asked questions
Who runs Twomey Cellars?
Twomey Cellars (PWSID CA2800555) is a transient non-community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Twomey Cellars serve?
Twomey Cellars reports serving 43 people through 1 service connection in Napa County, California.
Where does Twomey Cellars 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 Twomey Cellars have any drinking water violations?
EPA's records list 8 violations for this system; 1 is health-based, and the most recent began in July 2022. 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 Twomey Cellars' 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 8 violations for this system; 1 is health-based, and the most recent began in July 2022. For current results, consult EPA ECHO, or the CA state drinking water program.
Where can I find Twomey Cellars' water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Twomey Cellars is a transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Napa County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Napa, City of | Napa | 84,804 | Community | Surface water |
| American Canyon, City of | Napa | 21,437 | Community | Surface water |
| Phelps Vineyards | Napa | 19,412 | Non-transient non-community | Groundwater |
| Calistoga, City of | Napa | 5,610 | Community | Surface water |
| St. Helena, City of | Napa | 5,386 | Community | Surface water |
| Town of Yountville | Napa | 2,787 | 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, “Twomey Cellars, PWSID CA2800555, California”, https://aquacensus.com/water-systems/california/twomey-cellars-ca2800555 (data as of October 1, 2026).