Public water system · MT0000234
ActiveHamilton City of
At a glance
City of Hamilton (PWSID MT0000234) is an active community water system in Ravalli County, Montana. It reports serving 5,660 people through 2,443 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 10 violations for this system; none is health-based, and the most recent began in December 2017.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
5,660
Service connections
2,443
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Hamilton compare with other water systems in Ravalli County?
By EPA's size categories, City of Hamilton is a medium system (3,301 to 10,000 people). Ravalli County has 130 active public water systems, and City of Hamilton is the largest of them by population served. Its population served is about 24 times the county average of 237 people per system, and accounts for 18% of the 30,805 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Hamilton is about 16% 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. Montana has 853 active community water systems, 36% of the state's 2,378 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,994 Montana systems (84%) list groundwater as their primary source.
Who owns and regulates City of Hamilton?
EPA lists City of Hamilton as owned by a local government. The MT state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 9 of the 130 active systems in Ravalli County (6.9%) are also owned by a local government.
Does City of Hamilton have drinking water violations?
EPA's records list 10 violations for this system; none is health-based, and the most recent began in December 2017. The violations listed here began between January 1993 and December 2017. By type: 9 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Lead and Copper Rule (4 of them). EPA lists 10 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 |
|---|---|---|---|---|
| 2017-12-30 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2012-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | No | Resolved |
| 2011-12-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2006-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2001-10-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2001-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1996-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1994-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 1993-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1993-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
All 10 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.
City of Hamilton: frequently asked questions
Who runs City of Hamilton?
City of Hamilton (PWSID MT0000234) is a community water system owned by a local government. It is regulated by the MT state drinking water program.
How many people does City of Hamilton serve?
City of Hamilton reports serving 5,660 people through 2,443 service connections in Ravalli County, Montana.
Where does City of Hamilton 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 City of Hamilton have any drinking water violations?
EPA's records list 10 violations for this system; none is health-based, and the most recent began in December 2017. 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 City of Hamilton'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. EPA's records list 10 violations for this system; none is health-based, and the most recent began in December 2017. For current results, consult the system's annual water quality report, EPA ECHO, or the MT state drinking water program.
Where can I find City of Hamilton's water quality report?
As a community water system, City of Hamilton 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 Ravalli County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Stevensville Town of | Ravalli | 2,090 | Community | Groundwater |
| Super One Food Store | Ravalli | 1,769 | Non-transient non-community | Groundwater |
| Town Pump Woodside 1 | Ravalli | 1,198 | Transient non-community | Groundwater |
| Town Pump Florence 1 | Ravalli | 1,092 | Transient non-community | Groundwater |
| Florence Carlton School | Ravalli | 1,025 | Non-transient non-community | Groundwater |
| Corvallis Gym and Middle School | Ravalli | 900 | Non-transient non-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, “Hamilton City of, PWSID MT0000234, Montana”, https://aquacensus.com/water-systems/montana/hamilton-city-of-mt0000234 (data as of October 1, 2026).