PlainWater
States → Illinois

Community Water System · PWS IL0991150

Tonica

Tonica, Illinois 61370 - drinking water served from groundwater sources to 705 people, tracked in EPA SDWIS and UCMR5.

705
People served
129
EPA violations
85
Health-based
Untested
UCMR5 result

The verdict

EPA records 129 drinking-water violations at Tonica, 66% of them health-based - above the Illinois per-system average.

129
Total EPA violations on record
66%
Health-based (MCL / treatment failure)
705
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Tonica

Tonica is a local-owned community water system that delivers drinking water to 705 residents in Tonica, Illinois (LaSalle County) through 340 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 129 total violations for this system , of which 85 (66%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 31 monitoring and reporting violations are on file. The most recent violation on record dates to 2013.

The most frequently cited contaminant at this system is Arsenic, recorded in 72 violations (MCL, health-based). 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%).

Tonica's 129 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
705
Total Violations
129
Health-Based Violations
85
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
340
County
LaSalle
School/Daycare
No
MCL Violations
85
Monitoring Violations
31
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Arsenic MCL 72 2009
Coliform (TCR) MR 15 2012
Coliform (TCR) MCL 8 1997
Public Notice Other 6 2006
Chlorine MR 6 2012
Arsenic MR 5 2006
Nitrite MCL 5 2011
Nitrate MR 4 2005
Consumer Confidence Rule Other 2 2013
Gross Alpha, Excl. Radon and U MR 1 1977

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 Tonica.

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 IL0991150 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 Tonica 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
2013 Consumer Confidence Rule Other 2 SDWIS / IL0991150 / 7000
2012 Coliform (TCR) MR 15 SDWIS / IL0991150 / 3100
2012 Chlorine MR 6 SDWIS / IL0991150 / 0999
2011 Nitrite MCL 5 SDWIS / IL0991150 / 1041
2009 Arsenic MCL 72 SDWIS / IL0991150 / 1005
2006 Public Notice Other 6 SDWIS / IL0991150 / 7500
2006 Arsenic MR 5 SDWIS / IL0991150 / 1005
2005 Nitrate MR 4 SDWIS / IL0991150 / 1040
1997 Coliform (TCR) MCL 8 SDWIS / IL0991150 / 3100
1977 Gross Alpha, Excl. Radon and U MR 1 SDWIS / IL0991150 / 4000

How Tonica Compares

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

Metric Tonica Illinois avg Federal benchmark
Total violations 129 69.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 85 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 705 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 Tonica water safe to drink? ▼
Tonica (PWS ID: IL0991150) has 129 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 705 people using Groundwater sources.
How many people does Tonica serve? ▼
Tonica serves 705 people in Tonica, Illinois. It is a Local-owned system using Groundwater water sources with 340 service connections.
What type of violations does Tonica have? ▼
Tonica has 129 total violations: 85 health-based violations (MCL exceedances or treatment failures), 31 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Tonica water? ▼
No PFAS testing data is available for Tonica under the EPA's UCMR5 monitoring program.
What water source does Tonica use? ▼
Tonica 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.