Public water system · WI2680227
ActiveOconomowoc Waterworks
At a glance
Oconomowoc Waterworks (PWSID WI2680227) is an active community water system in Waukesha County, Wisconsin. It reports serving 15,805 people through 1 service connection. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 9 violations for this system; 3 are health-based, and the most recent began in January 2014.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
15,805
Service connections
1
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Oconomowoc Waterworks compare with other water systems in Waukesha County?
By EPA's size categories, Oconomowoc Waterworks is a large system (10,001 to 100,000 people). Waukesha County has 589 active public water systems, and Oconomowoc Waterworks is the 5th-largest of them by population served. Its population served is about 29 times the county average of 549 people per system, and accounts for 4.9% of the 323,265 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 Oconomowoc Waterworks is about 136% 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 Oconomowoc Waterworks?
EPA lists Oconomowoc 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. 102 of the 589 active systems in Waukesha County (17%) are also owned by a local government.
Does Oconomowoc Waterworks have drinking water violations?
EPA's records list 9 violations for this system; 3 are health-based, and the most recent began in January 2014. The violations listed here began between July 1992 and January 2014. By type: 4 monitoring and reporting, 3 contaminant level above the legal limit and 2 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (3 of them). EPA lists 9 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 |
|---|---|---|---|---|
| 2014-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2014-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2007-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2006-04-01 | Public notice, recordkeeping or otherPublic Notification Violation for NPDWR Violation · code 75 | Public Noticecode 7500 | No | Resolved |
| 2005-01-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2001-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1996-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1995-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1992-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
All 9 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.
Oconomowoc Waterworks: frequently asked questions
Who runs Oconomowoc Waterworks?
Oconomowoc Waterworks (PWSID WI2680227) is a community water system owned by a local government. It is regulated by the WI state drinking water program.
How many people does Oconomowoc Waterworks serve?
Oconomowoc Waterworks reports serving 15,805 people through 1 service connection in Waukesha County, Wisconsin.
Where does Oconomowoc 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 Oconomowoc Waterworks have any drinking water violations?
EPA's records list 9 violations for this system; 3 are health-based, and the most recent began in January 2014. 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 Oconomowoc 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. EPA's records list 9 violations for this system; 3 are health-based, and the most recent began in January 2014. For current results, consult the system's annual water quality report, EPA ECHO, or the WI state drinking water program.
Where can I find Oconomowoc Waterworks' water quality report?
As a community water system, Oconomowoc 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 Waukesha County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Waukesha Water Utility | Waukesha | 70,718 | Community | Purchased surface water |
| Brookfield Water Utility | Waukesha | 29,070 | Community | Groundwater |
| New Berlin Water Utility | Waukesha | 27,899 | Community | Purchased surface water |
| Menomonee Falls Ww - Surface Water | Waukesha | 23,867 | Community | Purchased surface water |
| Sussex Village Hall & Water Utility | Waukesha | 11,750 | Community | Groundwater |
| Hartland Waterworks | Waukesha | 9,212 | 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, “Oconomowoc Waterworks, PWSID WI2680227, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/oconomowoc-waterworks-wi2680227 (data as of October 1, 2026).