Public water system · IL1110100
ActiveCary
At a glance
Cary (PWSID IL1110100) is an active community water system in McHenry County, Illinois. It reports serving 17,826 people through 6,469 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, 6 are health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
17,826
Service connections
6,469
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Cary compare with other water systems in McHenry County?
By EPA's size categories, Cary is a large system (10,001 to 100,000 people). McHenry County has 192 active public water systems. Its population served is about 13 times the county average of 1,331 people per system, and accounts for 7% of the 255,516 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 Cary is about 166% 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. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 2,808 Illinois systems (73%) list groundwater as their primary source.
Who owns and regulates Cary?
EPA lists Cary 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. 35 of the 192 active systems in McHenry County (18%) are also owned by a local government.
Does Cary have drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in July 2025. The violations listed here began between October 1992 and July 2025. By type: 5 contaminant level above the legal limit, 4 monitoring and reporting, 2 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Total coliform bacteria (TCR) (4 of them). EPA lists 7 as resolved, 4 as archived and 1 as unaddressed. 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. 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 |
|---|---|---|---|---|
| 2025-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Unaddressed |
| 2016-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 1995-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Bariumcode 1010 | Yes | Resolved |
| 1995-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Bariumcode 1010 | Yes | Resolved |
| 1995-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Bariumcode 1010 | Yes | Resolved |
| 1993-06-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1993-04-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1992-12-21 | Required treatment not metOCCT/SOWT Study/Recommendation · code 57 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 1992-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-11-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-10-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | 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.
Cary: frequently asked questions
Who runs Cary?
Cary (PWSID IL1110100) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Cary serve?
Cary reports serving 17,826 people through 6,469 service connections in McHenry County, Illinois.
Where does Cary 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 Cary have any drinking water violations?
Of the 12 most recent violations in EPA's records, 6 are health-based, and the most recent began in July 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 Cary'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, 6 are health-based, and the most recent began in July 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Cary's water quality report?
As a community water system, Cary 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 McHenry County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Crystal Lake | McHenry | 40,661 | Community | Groundwater |
| Algonquin | McHenry | 30,700 | Community | Groundwater |
| Lake in the Hills | McHenry | 28,661 | Community | Groundwater |
| Huntley | McHenry | 28,495 | Community | Groundwater |
| Woodstock | McHenry | 25,630 | Community | Groundwater |
| Mchenry | McHenry | 22,335 | 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, “Cary, PWSID IL1110100, Illinois”, https://aquacensus.com/water-systems/illinois/cary-il1110100 (data as of October 1, 2026).