Public water system · IA9585017
ActiveThompson Water Works
At a glance
Thompson Water Works (PWSID IA9585017) is an active community water system in Winnebago County, Iowa. It reports serving 499 people through 312 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, one is health-based, and the most recent began in September 2004.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
499
Service connections
312
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Thompson Water Works compare with other water systems in Winnebago County?
By EPA's size categories, Thompson Water Works is a very small system (500 people or fewer). Winnebago County has 19 active public water systems, and Thompson Water Works is the 4th-largest of them by population served. Its population served is roughly in line with the county average of 496 people per system, and accounts for 5.3% of the 9,425 people reported by systems filed under the county. Across Iowa, the 1,828 active systems average 1,718 people each. Nationally, the average active community water system reports serving 6,703 people, so Thompson Water Works 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. Iowa has 1,084 active community water systems, 59% of the state's 1,828 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,502 Iowa systems (82%) list groundwater as their primary source.
Who owns and regulates Thompson Water Works?
EPA lists Thompson Water Works as owned by a local government. The IA 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 19 active systems in Winnebago County (42%) are also owned by a local government.
Does Thompson Water Works 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 2004. The violations listed here began between July 1986 and September 2004. By type: 11 monitoring and reporting and 1 contaminant level above the legal limit. The contaminant or rule involved most often is Arsenic (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 |
|---|---|---|---|---|
| 2004-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2001-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Vinyl chloridecode 2976 | No | Resolved |
| 2000-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 1989-04-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Seleniumcode 1045 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Chromiumcode 1020 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Bariumcode 1010 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Mercurycode 1035 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Fluoridecode 1025 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Cadmiumcode 1015 | No | Resolved |
| 1986-07-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | 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.
Thompson Water Works: frequently asked questions
Who runs Thompson Water Works?
Thompson Water Works (PWSID IA9585017) is a community water system owned by a local government. It is regulated by the IA state drinking water program.
How many people does Thompson Water Works serve?
Thompson Water Works reports serving 499 people through 312 service connections in Winnebago County, Iowa.
Where does Thompson Water Works 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 Thompson Water Works 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 2004. 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 Thompson Water Works' 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 2004. For current results, consult the system's annual water quality report, EPA ECHO, or the IA state drinking water program.
Where can I find Thompson Water Works' water quality report?
As a community water system, Thompson Water Works 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 Winnebago County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Forest City Water Supply | Winnebago | 4,285 | Community | Groundwater |
| Lake Mills Municipal Water Dept-South | Winnebago | 2,158 | Community | Groundwater |
| Buffalo Center Muni Water Dept | Winnebago | 857 | Community | Groundwater |
| Three Fingers Campground | Winnebago | 252 | Transient non-community | Groundwater |
| Leland Water Supply | Winnebago | 249 | Community | Groundwater |
| Rake Water Supply | Winnebago | 186 | 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, “Thompson Water Works, PWSID IA9585017, Iowa”, https://aquacensus.com/water-systems/iowa/thompson-water-works-ia9585017 (data as of October 1, 2026).