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Counties → Illinois

St. Clair County, Illinois

Water Systems
54
Population Served
258,141
Total Violations
3,100
298 health-based
PFAS Detected
8
of 10 tested

Violation Analysis

61.1%
Systems with Violations
57.4
Avg Violations per System
9.6%
Health-Based Violations

Water Source Types

SW
33 systems (61%)
GW
17 systems (31%)

PFAS Contamination

10
Systems Tested
8
PFAS Detected
80.0%
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

St. Clair Illinois water systems by violation status, EPA SDWIS records.

No violations on record (18) One or more violations (32)

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
IL American-East St Louis 131,368 12 Detected
O Fallon 46,603 102 Detected
Cahokia Heights 15,250 0 Detected
Caseyville 13,798 58 Detected
Mascoutah 8,759 43 Clean
American Water Oper and Maintenance, LLC 6,779 49 Detected
Lebanon 4,714 46 Clean
Freeburg 4,707 62 Detected
Dupo 4,684 8 Detected
Millstadt 4,071 57 Detected
Smithton 4,006 65 -
New Athens 1,970 42 -
Marissa 1,921 56 -
Prairie Dupont Pwd 1,863 35 -
Mound Pwd 1,500 67 -
Lenzburg 680 52 -
St Libory 628 66 -
Valley View Estates 580 5 -
Southwestern IL Correctional Center 563 0 -
Meadowbrook Mh Community, LLC 463 55 -
Fayetteville 441 171 -
S L M Water Commission 385 33 -
Arapaho Village MHP 368 0 -
Summerfield 347 46 -
Fsh Water Commission 313 44 -
Ildu Lepere MHP, LLC 250 35 -
St Clair County Foley Park 200 4 -
Karbans Knotty Pines 200 16 -
Children of Promise 50 1,724 -
St Michaels Church 50 11 -
Twice the Ice Freeburg 50 0 -
New Athens Hanft Pk Larry Webe 30 7 -
Schnucks (138297) 30 0 -
Schnucks (138313) 30 0 -
Schnucks (138321) 30 0 -
Walmart Supercenter 201 30 0 -
Twice the Ice Smithton 30 0 -
Millstadt Sportsmans Club 25 13 -
Quail Restoration Association 25 8 -
Schnucks 205 Belleville 25 0 -
New Baden Market Center 25 0 -
Schnucks #148 25 0 -
Dierbergs 25 0 -
Scarlett's Cabaret 25 25 -
Walmart Supercenter 1418 25 0 -
Fresh Thyme Farmers Market Fairview Hgts 25 0 -
Schnucks 177 O Fallon 25 0 -
Twice the Ice Mascoutah 25 0 -
Twice the Ice St Libory 25 4 -
Twice the Ice Fairview Heights 25 0 -

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
McHenry County
307 systems · 271,051 served · 11,554 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in St. Clair County? ▼
St. Clair County has 3,100 total drinking water violations across 54 water systems, of which 298 are health-based violations. 61.1% of systems have at least one violation.
How many people get water from St. Clair County systems? ▼
Water systems in St. Clair County serve approximately 258,141 people through 54 public water systems.
Has PFAS been detected in St. Clair County water? ▼
Of 10 water systems tested for PFAS in St. Clair County, 8 had PFAS detected (80.0% detection rate).
What types of water sources supply St. Clair County? ▼
Water systems in St. Clair County use SW (33 systems), GW (17 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. 9.6% of St. Clair 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.