Public water system · IL0313330
ActiveWinnetka
At a glance
Winnetka (PWSID IL0313330) is an active community water system in Cook County, Illinois. It reports serving 12,475 people through 4,477 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2010.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
12,475
Service connections
4,477
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does Winnetka compare with other water systems in Cook County?
By EPA's size categories, Winnetka is a large system (10,001 to 100,000 people). Cook County has 251 active public water systems. Its population served is about 41% below the county average of 20,993 people per system, and accounts for 0.2% of the 5,269,212 people reported by systems filed under the county. Across Illinois, the 3,872 active systems average 3,204 people each. Nationally, the average active community water system reports serving 6,703 people, so Winnetka is about 86% 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. Illinois has 1,773 active community water systems, 46% of the state's 3,872 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 89 Illinois systems (2.3%) list surface water as their primary source.
Who owns and regulates Winnetka?
EPA lists Winnetka as owned by a local government. The IL state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 134 of the 251 active systems in Cook County (53%) are also owned by a local government.
Does Winnetka have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2010. The violations listed here began between June 1977 and July 2010. By type: 11 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminants or rules involved are Consumer Confidence Rule, Total coliform bacteria (TCR), Chlorine and Arsenic. EPA lists 9 as archived and 3 as resolved. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2010-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2006-12-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2006-10-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Arseniccode 1005 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Mercurycode 1035 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Seleniumcode 1045 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Bariumcode 1010 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Chromiumcode 1020 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Fluoridecode 1025 | No | Archived |
| 1979-06-25 | Monitoring and reportingMonitoring, Regular · code 03 | Cadmiumcode 1015 | No | Archived |
| 1977-06-30 | Monitoring and reportingMonitoring, Regular · code 03 | 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.
Winnetka: frequently asked questions
Who runs Winnetka?
Winnetka (PWSID IL0313330) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Winnetka serve?
Winnetka reports serving 12,475 people through 4,477 service connections in Cook County, Illinois.
Where does Winnetka get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does Winnetka 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 July 2010. 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 Winnetka'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 July 2010. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Winnetka's water quality report?
As a community water system, Winnetka 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 Cook County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Chicago | Cook | 2,721,308 | Community | Surface water |
| Cicero | Cook | 83,000 | Community | Purchased surface water |
| Schaumburg | Cook | 75,750 | Community | Purchased surface water |
| Evanston | Cook | 74,486 | Community | Surface water |
| Arlington Heights | Cook | 73,320 | Community | Purchased surface water |
| Palatine | Cook | 70,875 | Community | Purchased 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, “Winnetka, PWSID IL0313330, Illinois”, https://aquacensus.com/water-systems/illinois/winnetka-il0313330 (data as of October 1, 2026).