Public water system · AZ0410179
ActiveGw Ocotillo Water - Thunderhead
At a glance
Gw Ocotillo Water - Thunderhead (PWSID AZ0410179) is an active community water system in Pima County, Arizona. It reports serving 174 people through 62 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in February 2013.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
174
Service connections
62
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Gw Ocotillo Water - Thunderhead compare with other water systems in Pima County?
By EPA's size categories, Gw Ocotillo Water - Thunderhead 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 Gw Ocotillo Water - Thunderhead 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 Gw Ocotillo Water - Thunderhead?
EPA lists Gw Ocotillo Water - Thunderhead as owned by a local government. 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. 33 of the 193 active systems in Pima County (17%) are also owned by a local government.
Does Gw Ocotillo Water - Thunderhead have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in February 2013. The violations listed here began between January 2001 and February 2013. By type: 8 monitoring and reporting and 4 public notice, recordkeeping or other. The contaminant or rule involved most often is Consumer Confidence Rule (4 of them). EPA lists 12 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 |
|---|---|---|---|---|
| 2013-02-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2007-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2006-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2005-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2004-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2004-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2003-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2002-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2002-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | No | Resolved |
| 2002-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | No | Resolved |
| 2001-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | No | Resolved |
| 2001-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbon tetrachloridecode 2982 | 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.
Gw Ocotillo Water - Thunderhead: frequently asked questions
Who runs Gw Ocotillo Water - Thunderhead?
Gw Ocotillo Water - Thunderhead (PWSID AZ0410179) is a community water system owned by a local government. It is regulated by the AZ state drinking water program.
How many people does Gw Ocotillo Water - Thunderhead serve?
Gw Ocotillo Water - Thunderhead reports serving 174 people through 62 service connections in Pima County, Arizona.
Where does Gw Ocotillo Water - Thunderhead 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 Gw Ocotillo Water - Thunderhead have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in February 2013. 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 Gw Ocotillo Water - Thunderhead'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, none is health-based, and the most recent began in February 2013. For current results, consult the system's annual water quality report, EPA ECHO, or the AZ state drinking water program.
Where can I find Gw Ocotillo Water - Thunderhead's water quality report?
As a community water system, Gw Ocotillo Water - Thunderhead 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, “Gw Ocotillo Water - Thunderhead, PWSID AZ0410179, Arizona”, https://aquacensus.com/water-systems/arizona/gw-ocotillo-water-thunderhead-az0410179 (data as of October 1, 2026).