PlainWater
Counties → Illinois

McHenry County, Illinois

Water Systems
307
Population Served
271,051
Total Violations
11,554
723 health-based
PFAS Detected
7
of 12 tested

Violation Analysis

84.4%
Systems with Violations
37.6
Avg Violations per System
6.3%
Health-Based Violations

Water Source Types

GW
50 systems (16%)

PFAS Contamination

12
Systems Tested
7
PFAS Detected
58.3%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

McHenry Illinois water systems by violation status, EPA SDWIS records.

No violations on record (4) One or more violations (46)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Crystal Lake 40,661 54 Detected
Algonquin 30,700 83 Clean
Lake in the Hills 28,661 52 Clean
Huntley 28,495 84 Clean
Woodstock 25,630 35 Clean
McHenry 22,335 101 Detected
Cary 17,826 66 Detected
Harvard 9,469 79 Clean
Prairie Path Water Co-Whispering Hills 8,300 76 Detected
Marengo 7,572 14 Detected
Fox River Grove 4,702 51 Detected
Lakewood 4,267 242 -
Wonder Lake 3,870 403 Clean
Richmond 2,087 58 -
Wonder Lake (Niu) 1,950 402 -
Aqua Illinois-McHenry Shores 1,862 265 -
Hebron 1,368 11 -
Prairie Path Water Company-Killarney 1,232 27 -
Johnsburg No.2 1,124 157 -
Prairie Grove School 1,050 147 -
Oakbrook Estates MHP 1,012 27 -
Prairie Path Water Company-Holiday Hills 868 19 -
Aqua Illinois-Crystal Clear Water Co. 855 418 -
Prairie Path Water Company-Walk Up Woods 775 27 -
Aqua Illinois-Eastwood Manor 728 309 -
Snap on Tools 700 35 -
IL American-Terra Cotta 681 0 -
Union 594 95 -
Johnsburg JR High School 575 61 -
Spring Grove Elementary School 500 103 -
St Peters Church 500 8 -
Lippold Park Con Softball Boncosky 500 0 -
Aqua Illinois-Nunda 485 194 -
Greenwood School 400 66 -
Illinois Turner Camp Pool 400 26 -
Resurrection Church 350 12 -
Cafe 31 North 300 9 -
Christ the King Church 300 11 -
Valley View School 300 176 -
Northwestern Medicine Woodstock Hospital 300 24 -
Scot Forge 253 68 -
Crystal Creek Farm 251 0 -
Crystal Lake Park D/W Herrick 250 0 -
Shiloh Church 250 96 -
Riverside Pub 220 15 -
Riley Community School 220 87 -
Kingdom Hall of Jehovahs Witnesses 219 2 -
Mary Ann Beebe Ctr/Activity Ctr (18226) 200 27 -
Crystal Lake Montessori 200 193 -
Big Foot Inn 200 8 -

Other Counties in Illinois

Cook County
427 systems · 5,304,996 served · 21,728 violations
DuPage County
207 systems · 861,775 served · 15,779 violations
Lake County
540 systems · 719,035 served · 33,311 violations
Will County
330 systems · 622,572 served · 37,818 violations
Kane County
191 systems · 592,544 served · 12,844 violations
Madison County
68 systems · 268,778 served · 1,940 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in McHenry County? ▼
McHenry County has 11,554 total drinking water violations across 307 water systems, of which 723 are health-based violations. 84.4% of systems have at least one violation.
How many people get water from McHenry County systems? ▼
Water systems in McHenry County serve approximately 271,051 people through 307 public water systems.
Has PFAS been detected in McHenry County water? ▼
Of 12 water systems tested for PFAS in McHenry County, 7 had PFAS detected (58.3% detection rate).
What types of water sources supply McHenry County? ▼
Water systems in McHenry County use GW (50 systems) as their primary water sources.
Are health-based violations serious? ▼
Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 6.3% of McHenry County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.