Public water system · IL0970250
ActiveGrayslake
At a glance
Grayslake (PWSID IL0970250) is an active community water system in Lake County, Illinois. It reports serving 21,248 people through 7,298 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 11 violations for this system; 6 are health-based, and the most recent began in July 2006.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
21,248
Service connections
7,298
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Grayslake compare with other water systems in Lake County?
By EPA's size categories, Grayslake is a large system (10,001 to 100,000 people). Lake County has 266 active public water systems. Its population served is about 8.7 times the county average of 2,442 people per system, and accounts for 3.3% of the 649,474 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 Grayslake is about 3.2 times 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. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 619 Illinois systems (16%) list purchased surface water as their primary source.
Who owns and regulates Grayslake?
EPA lists Grayslake 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. 60 of the 266 active systems in Lake County (23%) are also owned by a local government.
Does Grayslake have drinking water violations?
EPA's records list 11 violations for this system; 6 are health-based, and the most recent began in July 2006. The violations listed here began between June 1977 and July 2006. By type: 5 monitoring and reporting, 4 contaminant level above the legal limit and 2 required treatment not met. The contaminant or rule involved most often is Lead and Copper Rule (5 of them). EPA lists 6 as archived and 5 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 |
|---|---|---|---|---|
| 2006-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2000-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 2000-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1999-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1997-07-01 | Monitoring and reportingWater Quality Parameter M/R · code 53 | Lead and Copper Rulecode 5000 | No | Resolved |
| 1995-12-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1994-01-01 | Required treatment not metPublic Education · code 65 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 1992-12-21 | Required treatment not metOCCT/SOWT Study/Recommendation · code 57 | Lead and Copper Rulecode 5000 | Yes | Resolved |
| 1992-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1991-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1977-06-30 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Archived |
All 11 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.
Grayslake: frequently asked questions
Who runs Grayslake?
Grayslake (PWSID IL0970250) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Grayslake serve?
Grayslake reports serving 21,248 people through 7,298 service connections in Lake County, Illinois.
Where does Grayslake get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Grayslake have any drinking water violations?
EPA's records list 11 violations for this system; 6 are health-based, and the most recent began in July 2006. 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 Grayslake'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. EPA's records list 11 violations for this system; 6 are health-based, and the most recent began in July 2006. For current results, consult the system's annual water quality report, EPA ECHO, or the IL state drinking water program.
Where can I find Grayslake's water quality report?
As a community water system, Grayslake 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 Lake County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Waukegan | Lake | 87,149 | Community | Surface water |
| Vernon Hills - Lake Co Pw | Lake | 33,207 | Community | Purchased surface water |
| Mundelein | Lake | 31,500 | Community | Purchased surface water |
| Gurnee | Lake | 30,193 | Community | Purchased surface water |
| Highland Park | Lake | 30,176 | Community | Surface water |
| Round Lake Beach | Lake | 27,200 | 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, “Grayslake, PWSID IL0970250, Illinois”, https://aquacensus.com/water-systems/illinois/grayslake-il0970250 (data as of October 1, 2026).