Public water system · MT0003624
ActiveSwlo and Main Office
At a glance
Swlo and Main Office (PWSID MT0003624) is an active non-transient non-community water system in Missoula County, Montana. It reports serving 75 people through 2 service connections. Its primary water source is groundwater, and EPA lists it as owned by a state government. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in January 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
75
Service connections
2
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does Swlo and Main Office compare with other water systems in Missoula County?
By EPA's size categories, Swlo and Main Office is a very small system (500 people or fewer). Missoula County has 244 active public water systems. Its population served is well below the county average of 576 people per system, and accounts for less than 0.1% of the 140,505 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Swlo and Main Office 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. Montana has 319 active non-transient non-community water systems, 13% 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 Swlo and Main Office?
EPA lists Swlo and Main Office as owned by a state 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. 18 of the 244 active systems in Missoula County (7.4%) are also owned by a state government.
Does Swlo and Main Office have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in January 2025. The violations listed here began between January 2023 and January 2025. By type: 11 monitoring and reporting and 1 monitoring. The contaminant or rule involved most often is Nitrate-Nitrite (2 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 |
|---|---|---|---|---|
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | No | Resolved |
| 2024-11-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Heptachlor epoxidecode 2067 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Picloramcode 2040 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Chlorobenzenecode 2989 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Hexachlorocyclopentadienecode 2042 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbon tetrachloridecode 2982 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Toxaphenecode 2020 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Simazinecode 2037 | No | Resolved |
| 2023-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Seleniumcode 1045 | 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.
Swlo and Main Office: frequently asked questions
Who runs Swlo and Main Office?
Swlo and Main Office (PWSID MT0003624) is a non-transient non-community water system owned by a state government. It is regulated by the MT state drinking water program.
How many people does Swlo and Main Office serve?
Swlo and Main Office reports serving 75 people through 2 service connections in Missoula County, Montana.
Where does Swlo and Main Office 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 Swlo and Main Office have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in January 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 Swlo and Main Office'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, none is health-based, and the most recent began in January 2025. For current results, consult EPA ECHO, or the MT state drinking water program.
Where can I find Swlo and Main Office's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Swlo and Main Office 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 Missoula County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Missoula Water | Missoula | 68,200 | Community | Groundwater |
| University of Montana | Missoula | 15,000 | Non-transient non-community | Purchased groundwater |
| Lolo Water and Sewer Dist | Missoula | 3,315 | Community | Groundwater |
| Town Pump Bonner 1 | Missoula | 2,460 | Non-transient non-community | Groundwater |
| Clearwater Junction Rest Area | Missoula | 2,002 | Transient non-community | Groundwater |
| Seeley Lake Water District | Missoula | 1,575 | 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, “Swlo and Main Office, PWSID MT0003624, Montana”, https://aquacensus.com/water-systems/montana/swlo-and-main-office-mt0003624 (data as of October 1, 2026).