Public water system · 090400060
ActiveBia San Carlos
At a glance
Bia San Carlos (PWSID 090400060) is an active non-transient non-community water system in Arizona. It reports serving 2,150 people through 73 service connections. Its primary water source is groundwater, and EPA lists it as owned by the federal government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2026.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,150
Service connections
73
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Bia San Carlos compare with other water systems in Arizona?
By EPA's size categories, Bia San Carlos is a small system (501 to 3,300 people). Across Arizona, the 1,769 active systems average 4,369 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Bia San Carlos is about 5 times that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. Arizona has 232 active non-transient non-community water systems, 13% 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 Bia San Carlos?
EPA lists Bia San Carlos as owned by the federal government. The EPA Region 09 is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act.
Does Bia San Carlos have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2026. The violations listed here began between October 2023 and January 2026. By type: 8 reporting, 2 monitoring and reporting, 1 monitoring and 1 required treatment not met. The contaminant or rule involved most often is Revised Total Coliform Rule (8 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 |
|---|---|---|---|---|
| 2026-01-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2025-11-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2025-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2025-07-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 2024-11-16 | ReportingNotification, Known or Potential LSL · code 4H | Lead and Copper Rule Revisionscode 5200 | No | Unaddressed |
| 2024-10-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-08-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-06-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-04-19 | Required treatment not metFailure To Address Deficiency · code 45 | Groundwater Rulecode 0700 | Yes | Unaddressed |
| 2023-11-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2023-10-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | 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.
Bia San Carlos: frequently asked questions
Who runs Bia San Carlos?
Bia San Carlos (PWSID 090400060) is a non-transient non-community water system owned by the federal government. It is regulated by the EPA Region 09.
How many people does Bia San Carlos serve?
Bia San Carlos reports serving 2,150 people through 73 service connections in Arizona.
Where does Bia San Carlos 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 Bia San Carlos have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2026. 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 Bia San Carlos' 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, one is health-based, and the most recent began in January 2026. For current results, consult EPA ECHO, or the EPA Region 09.
Where can I find Bia San Carlos' water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Bia San Carlos is a non-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 Arizona
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Phoenix City of | Maricopa | 1,695,000 | Community | Surface water |
| Tucson City of | Pima | 732,906 | Community | Groundwater |
| Mesa City of | Maricopa | 466,000 | Community | Surface water |
| Gilbert, Town of | Maricopa | 247,600 | Community | Surface water |
| Chandler City of | Maricopa | 247,328 | Community | Surface water |
| Scottsdale City of | Maricopa | 241,361 | 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, “Bia San Carlos, PWSID 090400060, Arizona”, https://aquacensus.com/water-systems/arizona/bia-san-carlos-090400060 (data as of October 1, 2026).