Public water system · IL1330300
ActiveWaterloo
At a glance
Waterloo (PWSID IL1330300) is an active community water system in Monroe County, Illinois. It reports serving 10,190 people through 4,942 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, none is health-based, and the most recent began in April 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
10,190
Service connections
4,942
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Waterloo compare with other water systems in Monroe County?
By EPA's size categories, Waterloo is a large system (10,001 to 100,000 people). Monroe County has 13 active public water systems, and Waterloo is the 2nd-largest of them by population served. Its population served is about 4.9 times the county average of 2,096 people per system, and accounts for 37% of the 27,241 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 Waterloo is about 52% 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 Waterloo?
EPA lists Waterloo 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. 6 of the 13 active systems in Monroe County (46%) are also owned by a local government.
Does Waterloo have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 2025. The violations listed here began between April 2025 and April 2025. By type: 12 monitoring and reporting. The contaminants or rules involved are 1,2-Dichloropropane, Benzene, Nitrate and Styrene. EPA lists 12 as resolved. 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 |
|---|---|---|---|---|
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloropropanecode 2983 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzenecode 2990 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Styrenecode 2996 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Tetrachloroethylenecode 2987 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Vinyl chloridecode 2976 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Ethylbenzenecode 2992 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | trans-1,2-Dichloroethylenecode 2979 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloroethanecode 2980 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,1-Trichloroethanecode 2981 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbon tetrachloridecode 2982 | 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.
Waterloo: frequently asked questions
Who runs Waterloo?
Waterloo (PWSID IL1330300) is a community water system owned by a local government. It is regulated by the IL state drinking water program.
How many people does Waterloo serve?
Waterloo reports serving 10,190 people through 4,942 service connections in Monroe County, Illinois.
Where does Waterloo 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 Waterloo have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 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 Waterloo'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, none is health-based, and the most recent began in April 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 Waterloo's water quality report?
As a community water system, Waterloo 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 Monroe County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Columbia | Monroe | 11,129 | Community | Purchased surface water |
| Fountain Water District | Monroe | 3,650 | Community | Groundwater |
| Valmeyer | Monroe | 1,263 | Community | Purchased groundwater |
| Hecker | Monroe | 429 | Community | Purchased surface water |
| Maeystown | Monroe | 340 | Community | Purchased groundwater |
| Career Center of Southern Illinois | Monroe | 50 | Non-transient non-community | Groundwater |
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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, “Waterloo, PWSID IL1330300, Illinois”, https://aquacensus.com/water-systems/illinois/waterloo-il1330300 (data as of October 1, 2026).