Public water system · WI6420254
ActiveTomah Waterworks
At a glance
Tomah Waterworks (PWSID WI6420254) is an active community water system in Monroe County, Wisconsin. It reports serving 9,192 people through 3,139 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, 9 are health-based, and the most recent began in April 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
9,192
Service connections
3,139
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Tomah Waterworks compare with other water systems in Monroe County?
By EPA's size categories, Tomah Waterworks is a medium system (3,301 to 10,000 people). Monroe County has 102 active public water systems, and Tomah Waterworks is the 3rd-largest of them by population served. Its population served is about 24 times the county average of 385 people per system, and accounts for 23% of the 39,274 people reported by systems filed under the county. Across Wisconsin, the 11,056 active systems average 469 people each. Nationally, the average active community water system reports serving 6,703 people, so Tomah Waterworks is about 37% above 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. Wisconsin has 1,053 active community water systems, 9.5% of the state's 11,056 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 10,978 Wisconsin systems (99%) list groundwater as their primary source.
Who owns and regulates Tomah Waterworks?
EPA lists Tomah Waterworks as owned by a local government. The WI state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 14 of the 102 active systems in Monroe County (14%) are also owned by a local government.
Does Tomah Waterworks have drinking water violations?
Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in April 2025. The violations listed here began between July 2016 and April 2025. By type: 9 contaminant level above the legal limit and 3 public notice, recordkeeping or other. The contaminant or rule involved most often is Combined Radium (-226 and -228) (8 of them). EPA lists 11 as resolved 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. 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 |
|---|---|---|---|---|
| 2025-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Nitratecode 1040 | Yes | Archived |
| 2018-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2018-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2017-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2017-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2017-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2017-02-15 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2017-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2016-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Resolved |
| 2016-07-26 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2016-07-26 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2016-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | 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.
Tomah Waterworks: frequently asked questions
Who runs Tomah Waterworks?
Tomah Waterworks (PWSID WI6420254) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Tomah Waterworks serve?
Tomah Waterworks reports serving 9,192 people through 3,139 service connections in Monroe County, Wisconsin.
Where does Tomah Waterworks 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 Tomah Waterworks have any drinking water violations?
Of the 12 most recent violations in EPA's records, 9 are health-based, and the most recent began in April 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 Tomah Waterworks' 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, 9 are health-based, and the most recent began in April 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Tomah Waterworks' water quality report?
As a community water system, Tomah Waterworks 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 Monroe County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Sparta Waterworks | Monroe | 10,025 | Community | Groundwater |
| Fort Mccoy North Post | Monroe | 10,000 | Community | Groundwater |
| Cashton Waterworks | Monroe | 1,120 | Community | Groundwater |
| Brookwood High School | Monroe | 700 | Non-transient non-community | Groundwater |
| Norwalk Waterworks | Monroe | 653 | Community | Groundwater |
| Warrens Waterworks | Monroe | 540 | Community | Groundwater |
Related pages
Working with water-system records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
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, “Tomah Waterworks, PWSID WI6420254, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/tomah-waterworks-wi6420254 (data as of October 1, 2026).