Public water system · OH0904012
ActiveHamilton Public Water System
At a glance
Hamilton Public Water System (PWSID OH0904012) is an active community water system in Butler County, Ohio. It reports serving 62,447 people through 24,433 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, 4 are health-based, and the most recent began in December 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
62,447
Service connections
24,433
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Hamilton Public Water System compare with other water systems in Butler County?
By EPA's size categories, Hamilton Public Water System is a large system (10,001 to 100,000 people). Butler County has 20 active public water systems, and Hamilton Public Water System is the 2nd-largest of them by population served. Its population served is about 3.3 times the county average of 18,928 people per system, and accounts for 16% of the 378,564 people reported by systems filed under the county. Across Ohio, the 3,854 active systems average 2,767 people each. Nationally, the average active community water system reports serving 6,703 people, so Hamilton Public Water System is about 9.3 times 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. Ohio has 1,028 active community water systems, 27% 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 Hamilton Public Water System?
EPA lists Hamilton Public Water System as owned by a local government. 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. 8 of the 20 active systems in Butler County (40%) are also owned by a local government.
Does Hamilton Public Water System have drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in December 2025. The violations listed here began between June 1993 and December 2025. By type: 5 monitoring and reporting, 4 contaminant level above the legal limit and 3 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (4 of them). EPA lists 10 as resolved, 1 as unaddressed and 1 as archived. 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. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-12-30 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Unaddressed |
| 2025-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chloritecode 1009 | No | Archived |
| 2019-12-23 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2019-01-10 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2005-06-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chloritecode 1009 | No | Resolved |
| 2005-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chloritecode 1009 | No | Resolved |
| 2002-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 1997-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1997-03-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1994-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1993-07-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1993-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | 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.
Hamilton Public Water System: frequently asked questions
Who runs Hamilton Public Water System?
Hamilton Public Water System (PWSID OH0904012) is a community water system owned by a local government. It is regulated by the OH state drinking water program.
How many people does Hamilton Public Water System serve?
Hamilton Public Water System reports serving 62,447 people through 24,433 service connections in Butler County, Ohio.
Where does Hamilton Public Water System 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 Hamilton Public Water System have any drinking water violations?
Of the 12 most recent violations in EPA's records, 4 are health-based, and the most recent began in December 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 Hamilton Public Water System'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, 4 are health-based, and the most recent began in December 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the OH state drinking water program.
Where can I find Hamilton Public Water System's water quality report?
As a community water system, Hamilton Public Water System 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 Butler County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Butler Co. Water District 2 Pws | Butler | 116,572 | Community | Purchased surface water |
| Middletown City Pws | Butler | 51,229 | Community | Groundwater |
| Fairfield City Pws | Butler | 44,907 | Community | Groundwater |
| Southwest Regional Water District | Butler | 42,856 | Community | Groundwater |
| Oxford City Pws | Butler | 24,000 | Community | Groundwater |
| Monroe City Pws | Butler | 15,600 | Community | Purchased 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, “Hamilton Public Water System, PWSID OH0904012, Ohio”, https://aquacensus.com/water-systems/ohio/hamilton-public-water-system-oh0904012 (data as of October 1, 2026).