Public water system · IL1630800
ActiveMascoutah
At a glance
Mascoutah (PWSID IL1630800) is an active community water system in St. Clair County, Illinois. It reports serving 8,759 people through 3,992 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 8 violations for this system; 4 are health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
8,759
Service connections
3,992
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Mascoutah compare with other water systems in St. Clair County?
By EPA's size categories, Mascoutah is a medium system (3,301 to 10,000 people). St. Clair County has 42 active public water systems, and Mascoutah is the 5th-largest of them by population served. Its population served is about 44% above the county average of 6,082 people per system, and accounts for 3.4% of the 255,459 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 Mascoutah is about 31% 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. 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 Mascoutah?
EPA lists Mascoutah 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. 22 of the 42 active systems in St. Clair County (52%) are also owned by a local government.
Does Mascoutah have drinking water violations?
EPA's records list 8 violations for this system; 4 are health-based, and the most recent began in July 2025. The violations listed here began between June 1991 and July 2025. By type: 3 contaminant level above the legal limit, 3 monitoring and reporting, 1 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Total coliform bacteria (TCR) (5 of them). EPA lists 4 as archived, 3 as resolved and 1 as unaddressed. 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. 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 |
| 2014-06-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Long Term 2 Enhanced Surface Water Treatment Rulecode 0800 | Yes | Resolved |
| 2005-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1997-01-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1996-06-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1995-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Atrazinecode 2050 | Yes | Resolved |
| 1994-06-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1991-06-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
All 8 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.
Mascoutah: frequently asked questions
Who runs Mascoutah?
Mascoutah (PWSID IL1630800) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Mascoutah serve?
Mascoutah reports serving 8,759 people through 3,992 service connections in St. Clair County, Illinois.
Where does Mascoutah 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 Mascoutah have any drinking water violations?
EPA's records list 8 violations for this system; 4 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 Mascoutah'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 8 violations for this system; 4 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 Mascoutah's water quality report?
As a community water system, Mascoutah 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 St. Clair County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Il American-East St Louis | St. Clair | 131,368 | Community | Surface water |
| O Fallon | St. Clair | 46,603 | Community | Purchased surface water |
| Caseyville | St. Clair | 13,798 | Community | Purchased surface water |
| Cahokia Heights | St. Clair | 12,528 | Community | Purchased surface water |
| American Water Oper and Maintenance, LLC | St. Clair | 6,779 | Community | Purchased surface water |
| Lebanon | St. Clair | 4,714 | 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, “Mascoutah, PWSID IL1630800, Illinois”, https://aquacensus.com/water-systems/illinois/mascoutah-il1630800 (data as of October 1, 2026).