Public water system · AZ0410286
ActiveRancho Sierrita Well Assoc
At a glance
Rancho Sierrita Well Assoc (PWSID AZ0410286) is an active community water system in Pima County, Arizona. It reports serving 55 people through 30 service connections. Its primary water source is groundwater, and EPA lists it as under public/private ownership. Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in October 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
55
Service connections
30
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Rancho Sierrita Well Assoc compare with other water systems in Pima County?
By EPA's size categories, Rancho Sierrita Well Assoc is a very small system (500 people or fewer). Pima County has 193 active public water systems. Its population served is well below the county average of 5,896 people per system, and accounts for less than 0.1% of the 1,137,975 people reported by systems filed under the county. Across Arizona, the 1,769 active systems average 4,369 people each. Nationally, the average active community water system reports serving 6,703 people, so Rancho Sierrita Well Assoc 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. Arizona has 936 active community water systems, 53% of the state's 1,769 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,612 Arizona systems (91%) list groundwater as their primary source.
Who owns and regulates Rancho Sierrita Well Assoc?
EPA lists Rancho Sierrita Well Assoc as under public/private ownership. The AZ state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 70 of the 193 active systems in Pima County (36%) are also under public/private ownership.
Does Rancho Sierrita Well Assoc have drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in October 2025. The violations listed here began between June 2017 and October 2025. By type: 5 monitoring and reporting, 5 reporting, 1 contaminant level above the legal limit and 1 required treatment not met. The contaminant or rule involved most often is Revised Total Coliform Rule (7 of them). EPA lists 10 as resolved and 2 as unaddressed. 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. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Unaddressed |
| 2024-03-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-01-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2022-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2019-08-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2019-07-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2018-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2017-11-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2017-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, E. coli (RTCR) · code 1A | Revised Total Coliform Rulecode 8000 | Yes | Resolved |
| 2017-07-09 | Required treatment not metTreatment Technique, Level 1 Assessment (RTCR) · code 2A | Revised Total Coliform Rulecode 8000 | Yes | Unaddressed |
| 2017-06-21 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | 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 Sierrita Well Assoc: frequently asked questions
Who runs Rancho Sierrita Well Assoc?
Rancho Sierrita Well Assoc (PWSID AZ0410286) is a community water system under public/private ownership. It is regulated by the AZ state drinking water program.
How many people does Rancho Sierrita Well Assoc serve?
Rancho Sierrita Well Assoc reports serving 55 people through 30 service connections in Pima County, Arizona.
Where does Rancho Sierrita Well Assoc 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 Sierrita Well Assoc have any drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in October 2025. 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 Sierrita Well Assoc'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, 2 are health-based, and the most recent began in October 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the AZ state drinking water program.
Where can I find Rancho Sierrita Well Assoc's water quality report?
As a community water system, Rancho Sierrita Well Assoc 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 Pima County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Tucson City of | Pima | 732,906 | Community | Groundwater |
| University of Arizona | Pima | 50,000 | Non-transient non-community | Groundwater |
| Metropolitan Dwid | Pima | 45,570 | Community | Groundwater |
| Oro Valley Water Utility | Pima | 42,316 | Community | Groundwater |
| Community Wc of Green Valley | Pima | 22,085 | Community | Groundwater |
| Usaf Davis Monthan Afb | Pima | 18,640 | 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, “Rancho Sierrita Well Assoc, PWSID AZ0410286, Arizona”, https://aquacensus.com/water-systems/arizona/rancho-sierrita-well-assoc-az0410286 (data as of October 1, 2026).