Public water system · AZ0403362
ActiveHidden Hollow Mhc
At a glance
Hidden Hollow Mhc (PWSID AZ0403362) is an active community water system in Coconino County, Arizona. It reports serving 400 people through 120 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, one is health-based, and the most recent began in September 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
400
Service connections
120
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Hidden Hollow Mhc compare with other water systems in Coconino County?
By EPA's size categories, Hidden Hollow Mhc is a very small system (500 people or fewer). Coconino County has 114 active public water systems. Its population served is well below the county average of 1,573 people per system, and accounts for 0.2% of the 179,316 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 Hidden Hollow Mhc 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 Hidden Hollow Mhc?
EPA lists Hidden Hollow Mhc 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. 45 of the 114 active systems in Coconino County (39%) are also under public/private ownership.
Does Hidden Hollow Mhc have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in September 2024. The violations listed here began between October 2007 and September 2024. By type: 8 monitoring and reporting, 2 reporting, 1 required treatment not met and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Revised Total Coliform Rule (3 of them). EPA lists 11 as resolved and 1 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 |
|---|---|---|---|---|
| 2024-09-08 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2024-06-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2022-10-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 2021-08-23 | Required treatment not metTreatment Technique, Level 2 Assessment (RTCR) · code 2B | Revised Total Coliform Rulecode 8000 | Yes | Unaddressed |
| 2017-03-01 | ReportingReport Sample Result/Fail Monitor (RTCR) · code 4B | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2015-08-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2015-07-29 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2011-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 2010-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 2008-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2008-03-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2007-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | 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.
Hidden Hollow Mhc: frequently asked questions
Who runs Hidden Hollow Mhc?
Hidden Hollow Mhc (PWSID AZ0403362) is a community water system under public/private ownership. It is regulated by the AZ state drinking water program.
How many people does Hidden Hollow Mhc serve?
Hidden Hollow Mhc reports serving 400 people through 120 service connections in Coconino County, Arizona.
Where does Hidden Hollow Mhc 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 Hidden Hollow Mhc 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 September 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 Hidden Hollow Mhc'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, one is health-based, and the most recent began in September 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the AZ state drinking water program.
Where can I find Hidden Hollow Mhc's water quality report?
As a community water system, Hidden Hollow Mhc 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 Coconino County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Flagstaff City of | Coconino | 79,796 | Community | Surface water |
| Grand Canyon National Park | Coconino | 16,590 | Community | Groundwater |
| Arizona Water Co - Sedona | Coconino | 12,104 | Community | Groundwater |
| Doney Park Water | Coconino | 8,996 | Community | Groundwater |
| Arizona Water Co - Pinewood | Coconino | 8,089 | Community | Groundwater |
| Page City of | Coconino | 7,420 | Community | Surface water |
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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, “Hidden Hollow Mhc, PWSID AZ0403362, Arizona”, https://aquacensus.com/water-systems/arizona/hidden-hollow-mhc-az0403362 (data as of October 1, 2026).