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Community Water System · PWS IL0735200

Osco Mutual Water Supply Company, Inc.

Osco, Illinois 61274 - drinking water served from groundwater sources to 80 people, tracked in EPA SDWIS and UCMR5.

80
People served
103
EPA violations
2
Health-based
Untested
UCMR5 result

The verdict

EPA records 103 drinking-water violations at Osco Mutual Water Supply Company, Inc., 2% of them health-based - above the Illinois per-system average.

103
Total EPA violations on record
2%
Health-based (MCL / treatment failure)
80
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Osco Mutual Water Supply Company, Inc.

Osco Mutual Water Supply Company, Inc. is a private-owned community water system that delivers drinking water to 80 residents in Osco, Illinois (Henry County) through 50 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 103 total violations for this system , of which 2 (2%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 53 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.

The most frequently cited contaminant at this system is Chlorine, recorded in 14 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Illinois, EPA tracks 5,117 public water systems serving 12,576,876 people, with 355,322 cumulative violations and 52,932 health-based violations on record. About 81% of systems in the state carry at least one violation, and state-wide the average per system is 69.4 violations. Statewide, 199 of 487 UCMR5-tested systems have reported PFAS detections (40.9%).

Osco Mutual Water Supply Company, Inc.'s 103 violations sit above the Illinois average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
80
Total Violations
103
Health-Based Violations
2
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
50
County
Henry
School/Daycare
No
MCL Violations
2
Monitoring Violations
53
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Chlorine MR 14 2008
Public Notice Other 6 2005
Selenium MR 4 1983
Arsenic MR 4 1983
Barium MR 4 1983
Cadmium MR 4 1983
Fluoride MR 4 1983
Coliform (TCR) MR 4 2007
Nitrate MR 4 1983
Chromium MR 4 1983
Mercury MR 4 1983
Lead and Copper Rule MR 2 2011
Coliform (TCR) MCL 2 2002
LEAD AND COPPER RULE REVISIONS RPT 2 2025
Gross Alpha, Excl. Radon and U MR 1 1977
Consumer Confidence Rule Other 1 2025

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Osco Mutual Water Supply Company, Inc..

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID IL0735200 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Illinois Drinking Water Authority

Illinois EPA, Bureau of Water is the primacy agency that licenses and inspects Osco Mutual Water Supply Company, Inc. under EPA-delegated authority.

Open IL regulator portal

Source: Illinois EPA, Bureau of Water

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2025 LEAD AND COPPER RULE REVISIONS RPT 2 SDWIS / IL0735200 / 5200
2025 Consumer Confidence Rule Other 1 SDWIS / IL0735200 / 7000
2011 Lead and Copper Rule MR 2 SDWIS / IL0735200 / 5000
2008 Chlorine MR 14 SDWIS / IL0735200 / 0999
2007 Coliform (TCR) MR 4 SDWIS / IL0735200 / 3100
2005 Public Notice Other 6 SDWIS / IL0735200 / 7500
2002 Coliform (TCR) MCL 2 SDWIS / IL0735200 / 3100
1983 Selenium MR 4 SDWIS / IL0735200 / 1045
1983 Arsenic MR 4 SDWIS / IL0735200 / 1005
1983 Barium MR 4 SDWIS / IL0735200 / 1010
1983 Cadmium MR 4 SDWIS / IL0735200 / 1015
1983 Fluoride MR 4 SDWIS / IL0735200 / 1025
1983 Nitrate MR 4 SDWIS / IL0735200 / 1040
1983 Chromium MR 4 SDWIS / IL0735200 / 1020
1983 Mercury MR 4 SDWIS / IL0735200 / 1035

How Osco Mutual Water Supply Company, Inc. Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Osco Mutual Water Supply Company, Inc. Illinois avg Federal benchmark
Total violations 103 69.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 2 10.3 Indicates a contaminant exceeded a federal MCL
PFAS detection None 40.9% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 80 2,458 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 5,117 regulated public water systems in Illinois.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Osco Mutual Water Supply Company, Inc. water safe to drink? ▼
Osco Mutual Water Supply Company, Inc. (PWS ID: IL0735200) has 103 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 80 people using Groundwater sources.
How many people does Osco Mutual Water Supply Company, Inc. serve? ▼
Osco Mutual Water Supply Company, Inc. serves 80 people in Osco, Illinois. It is a Private-owned system using Groundwater water sources with 50 service connections.
What type of violations does Osco Mutual Water Supply Company, Inc. have? ▼
Osco Mutual Water Supply Company, Inc. has 103 total violations: 2 health-based violations (MCL exceedances or treatment failures), 53 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Osco Mutual Water Supply Company, Inc. water? ▼
No PFAS testing data is available for Osco Mutual Water Supply Company, Inc. under the EPA's UCMR5 monitoring program.
What water source does Osco Mutual Water Supply Company, Inc. use? ▼
Osco Mutual Water Supply Company, Inc. uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

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 system's figures are rendered directly from 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.