Public water system · WI1280104
ActiveJefferson Waterworks
At a glance
Jefferson Waterworks (PWSID WI1280104) is an active community water system in Jefferson County, Wisconsin. It reports serving 7,926 people through 3,072 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 October 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
7,926
Service connections
3,072
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Jefferson Waterworks compare with other water systems in Jefferson County?
By EPA's size categories, Jefferson Waterworks is a medium system (3,301 to 10,000 people). Jefferson County has 195 active public water systems, and Jefferson Waterworks is the 3rd-largest of them by population served. Its population served is about 17 times the county average of 453 people per system, and accounts for 9% of the 88,343 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 Jefferson Waterworks is about 18% 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 Jefferson Waterworks?
EPA lists Jefferson 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. 34 of the 195 active systems in Jefferson County (17%) are also owned by a local government.
Does Jefferson 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 October 2024. The violations listed here began between February 2002 and October 2024. By type: 9 contaminant level above the legal limit, 2 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Combined Radium (-226 and -228) (7 of them). EPA lists 8 as archived, 3 as resolved and 1 as unaddressed. 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. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2024-10-01 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2024-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2024-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2023-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2023-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2023-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2023-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2022-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Combined Radium (-226 and -228)code 4010 | Yes | Archived |
| 2010-05-10 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Unaddressed |
| 2010-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Gross alpha (excluding radon and uranium)code 4000 | Yes | Resolved |
| 2009-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Gross alpha (excluding radon and uranium)code 4000 | Yes | Resolved |
| 2002-02-28 | Monitoring and reportingMonitoring, Check/Repeat/Confirmation · code 04 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
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.
Jefferson Waterworks: frequently asked questions
Who runs Jefferson Waterworks?
Jefferson Waterworks (PWSID WI1280104) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Jefferson Waterworks serve?
Jefferson Waterworks reports serving 7,926 people through 3,072 service connections in Jefferson County, Wisconsin.
Where does Jefferson 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 Jefferson 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 October 2024. 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 Jefferson 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 October 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Jefferson Waterworks' water quality report?
As a community water system, Jefferson 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 Jefferson County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Watertown Waterworks | Jefferson | 23,945 | Community | Groundwater |
| Fort Atkinson Waterworks | Jefferson | 12,390 | Community | Groundwater |
| Lake Mills Waterworks | Jefferson | 6,211 | Community | Groundwater |
| Waterloo Waterworks | Jefferson | 3,520 | Community | Groundwater |
| Johnson Creek Waterworks | Jefferson | 3,318 | Community | Groundwater |
| Wi Dot Rest Area 13 Aztalan | Jefferson | 1,904 | 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, “Jefferson Waterworks, PWSID WI1280104, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/jefferson-waterworks-wi1280104 (data as of October 1, 2026).