Public water system · CA3700918
ActiveRancho Santa Teresa Mw Co.
At a glance
Rancho Santa Teresa Mw Co. (PWSID CA3700918) is an active community water system in San Diego County, California. It reports serving 102 people through 38 service connections. Its primary water source is groundwater, 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 October 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
102
Service connections
38
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Rancho Santa Teresa Mw Co. compare with other water systems in San Diego County?
By EPA's size categories, Rancho Santa Teresa Mw Co. is a very small system (500 people or fewer). San Diego County has 191 active public water systems. Its population served is well below the county average of 19,427 people per system, and accounts for less than 0.1% of the 3,710,459 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 Rancho Santa Teresa Mw Co. 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 Rancho Santa Teresa Mw Co.?
EPA lists Rancho Santa Teresa Mw Co. 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. 101 of the 191 active systems in San Diego County (53%) are also privately owned.
Does Rancho Santa Teresa Mw Co. have drinking water violations?
Of the 12 most recent violations in EPA's records, 3 are health-based, and the most recent began in October 2024. The violations listed here began between October 2021 and October 2024. By type: 7 monitoring, 3 contaminant level above the legal limit, 1 public notice, recordkeeping or other and 1 monitoring and reporting. The contaminant or rule involved most often is Revised Total Coliform Rule (7 of them). EPA lists 7 as resolved and 5 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 |
|---|---|---|---|---|
| 2024-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Single Sample · code 01 | Nitratecode 1040 | Yes | Archived |
| 2023-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Single Sample · code 01 | Nitratecode 1040 | Yes | Archived |
| 2023-08-29 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2023-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Single Sample · code 01 | Nitratecode 1040 | Yes | Archived |
| 2022-07-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-06-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2022-05-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Archived |
| 2022-04-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2022-02-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-01-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2021-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
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.
Rancho Santa Teresa Mw Co.: frequently asked questions
Who runs Rancho Santa Teresa Mw Co.?
Rancho Santa Teresa Mw Co. (PWSID CA3700918) is a community water system privately owned. It is regulated by the CA state drinking water program.
How many people does Rancho Santa Teresa Mw Co. serve?
Rancho Santa Teresa Mw Co. reports serving 102 people through 38 service connections in San Diego County, California.
Where does Rancho Santa Teresa Mw Co. 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 Rancho Santa Teresa Mw Co. 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 October 2024. 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 Rancho Santa Teresa Mw Co.'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 October 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Rancho Santa Teresa Mw Co.'s water quality report?
As a community water system, Rancho Santa Teresa Mw Co. 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 Diego County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| San Diego, City of | San Diego | 1,385,379 | Community | Surface water |
| Helix Water District | San Diego | 277,668 | Community | Surface water |
| Otay Water District | San Diego | 238,008 | Community | Purchased surface water |
| Sweetwater Authority | San Diego | 191,282 | Community | Surface water |
| Oceanside, City of | San Diego | 171,483 | Community | Purchased surface water |
| Escondido, City of | San Diego | 137,044 | Community | 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, “Rancho Santa Teresa Mw Co., PWSID CA3700918, California”, https://aquacensus.com/water-systems/california/rancho-santa-teresa-mw-co-ca3700918 (data as of October 1, 2026).