Public water system · OH2900112
ActiveMount St. John
At a glance
Mount St. John (PWSID OH2900112) is an active non-transient non-community water system in Greene County, Ohio. It reports serving 115 people through 6 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, one is health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
115
Service connections
6
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Mount St. John compare with other water systems in Greene County?
By EPA's size categories, Mount St. John is a very small system (500 people or fewer). Greene County has 46 active public water systems. Its population served is well below the county average of 2,234 people per system, and accounts for 0.1% of the 102,782 people reported by systems filed under the county. Across Ohio, the 3,854 active systems average 2,767 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Mount St. John is well below 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. Ohio has 544 active non-transient non-community water systems, 14% of the state's 3,854 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 3,446 Ohio systems (89%) list groundwater as their primary source.
Who owns and regulates Mount St. John?
EPA lists Mount St. John as privately owned. The OH state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 34 of the 46 active systems in Greene County (74%) are also privately owned.
Does Mount St. John have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in July 2025. The violations listed here began between January 1999 and July 2025. By type: 9 monitoring and reporting, 2 reporting and 1 required treatment not met. The contaminant or rule involved most often is Lead and Copper Rule Revisions (3 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 |
|---|---|---|---|---|
| 2025-07-02 | ReportingNotification, Known or Potential LSL · code 4H | Lead and Copper Rule Revisionscode 5200 | No | Resolved |
| 2024-10-17 | Required treatment not metLSL Inventory · code 2E | Lead and Copper Rule Revisionscode 5200 | Yes | Resolved |
| 2024-10-17 | ReportingLSL Reporting · code 4G | Lead and Copper Rule Revisionscode 5200 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Styrenecode 2996 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | cis-1,2-Dichloroethylenecode 2380 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1-Dichloroethylenecode 2977 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzenecode 2990 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Tetrachloroethylenecode 2987 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,1-Trichloroethanecode 2981 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloropropanecode 2983 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloroethanecode 2980 | No | Resolved |
| 1999-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Toluenecode 2991 | 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.
Mount St. John: frequently asked questions
Who runs Mount St. John?
Mount St. John (PWSID OH2900112) is a non-transient non-community water system privately owned. It is regulated by the OH state drinking water program.
How many people does Mount St. John serve?
Mount St. John reports serving 115 people through 6 service connections in Greene County, Ohio.
Where does Mount St. John 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 Mount St. John 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 July 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 Mount St. John'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 July 2025. For current results, consult EPA ECHO, or the OH state drinking water program.
Where can I find Mount St. John's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Mount St. John 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 Greene County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Fairborn Public Water System | Greene | 34,620 | Community | Groundwater |
| Xenia City Pws | Greene | 29,000 | Community | Groundwater |
| Bellbrook Water Works | Greene | 9,475 | Community | Groundwater |
| Wright State University | Greene | 8,948 | Community | Groundwater |
| Cedarville University | Greene | 4,000 | Community | Groundwater |
| Yellow Springs Village Pws | Greene | 3,761 | 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, “Mount St. John, PWSID OH2900112, Ohio”, https://aquacensus.com/water-systems/ohio/mount-st-john-oh2900112 (data as of October 1, 2026).