Public water system · CA4900647
ActiveSereno Del Mar Water Company (Puc)
At a glance
Sereno Del Mar Water Company (Puc) (PWSID CA4900647) is an active community water system in Sonoma County, California. It reports serving 435 people through 139 service connections. Its primary water source is surface water, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in January 2007.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
435
Service connections
139
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Sereno Del Mar Water Company (Puc) compare with other water systems in Sonoma County?
By EPA's size categories, Sereno Del Mar Water Company (Puc) is a very small system (500 people or fewer). Sonoma County has 441 active public water systems. Its population served is about 60% 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 Sereno Del Mar Water Company (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. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 609 California systems (8.1%) list surface water as their primary source.
Who owns and regulates Sereno Del Mar Water Company (Puc)?
EPA lists Sereno Del Mar Water Company (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 Sereno Del Mar Water Company (Puc) have drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in January 2007. The violations listed here began between October 1981 and January 2007. By type: 5 public notice, recordkeeping or other, 4 monitoring and reporting, 2 required treatment not met and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Surface Water Treatment Rule (2 of them). EPA lists 6 as resolved and 6 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 |
|---|---|---|---|---|
| 2007-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitritecode 1041 | No | Resolved |
| 2006-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2001-12-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2000-02-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1999-02-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 1993-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1984-09-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1984-07-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1983-05-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1982-11-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1982-10-01 | Public notice, recordkeeping or otherNotification, Public · code 06 | Not reported | No | Archived |
| 1981-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
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.
Sereno Del Mar Water Company (Puc): frequently asked questions
Who runs Sereno Del Mar Water Company (Puc)?
Sereno Del Mar Water Company (Puc) (PWSID CA4900647) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Sereno Del Mar Water Company (Puc) serve?
Sereno Del Mar Water Company (Puc) reports serving 435 people through 139 service connections in Sonoma County, California.
Where does Sereno Del Mar Water Company (Puc) get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Sereno Del Mar Water Company (Puc) have any drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in January 2007. 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 Sereno Del Mar Water Company (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. Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in January 2007. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Sereno Del Mar Water Company (Puc)'s water quality report?
As a community water system, Sereno Del Mar Water Company (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, “Sereno Del Mar Water Company (Puc), PWSID CA4900647, California”, https://aquacensus.com/water-systems/california/sereno-del-mar-water-company-puc-ca4900647 (data as of October 1, 2026).