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Community Water System · PWS IL0950450

Rio

Rio, Illinois 61472 - drinking water served from groundwater sources to 265 people, tracked in EPA SDWIS and UCMR5.

265
People served
165
EPA violations
15
Health-based
Untested
UCMR5 result

The verdict

EPA records 165 drinking-water violations at Rio, 9% of them health-based - above the Illinois per-system average.

165
Total EPA violations on record
9%
Health-based (MCL / treatment failure)
265
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Rio

Rio is a local-owned community water system that delivers drinking water to 265 residents in Rio, Illinois (Knox County) through 106 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 165 total violations for this system , of which 15 (9%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 121 monitoring and reporting violations are on file. The most recent violation on record dates to 2008.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 26 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%).

Rio's 165 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
265
Total Violations
165
Health-Based Violations
15
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
106
County
Knox
School/Daycare
No
MCL Violations
15
Monitoring Violations
121
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 26 2008
Fluoride MCL 15 1984
Arsenic MR 4 1986
Cadmium MR 4 1986
Fluoride MR 4 1986
Nitrate MR 4 1986
Selenium MR 4 1986
Barium MR 4 1986
Mercury MR 4 1986
Chromium MR 4 1986
cis-1,2-Dichloroethylene MR 3 1994
Xylenes, Total MR 3 1994
o-Dichlorobenzene MR 3 1994
1,2-Dichloropropane MR 3 1994
Tetrachloroethylene MR 3 1994
Toluene MR 3 1994
Ethylbenzene MR 3 1994
1,2,4-Trichlorobenzene MR 3 1994
1,1,2-Trichloroethane MR 3 1994
1,2-Dichloroethane MR 3 1994
trans-1,2-Dichloroethylene MR 3 1994
DICHLOROMETHANE MR 3 1994
1,1-Dichloroethylene MR 3 1994
p-Dichlorobenzene MR 3 1994
CHLOROBENZENE MR 3 1994
Carbon tetrachloride MR 3 1994
Trichloroethylene MR 3 1994
Styrene MR 3 1994
1,1,1-Trichloroethane MR 3 1994
Benzene MR 3 1994

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 Rio.

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 IL0950450 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 Rio 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
2008 Coliform (TCR) MR 26 SDWIS / IL0950450 / 3100
1995 Lead and Copper Rule MR 2 SDWIS / IL0950450 / 5000
1994 cis-1,2-Dichloroethylene MR 3 SDWIS / IL0950450 / 2380
1994 Xylenes, Total MR 3 SDWIS / IL0950450 / 2955
1994 o-Dichlorobenzene MR 3 SDWIS / IL0950450 / 2968
1994 1,2-Dichloropropane MR 3 SDWIS / IL0950450 / 2983
1994 Tetrachloroethylene MR 3 SDWIS / IL0950450 / 2987
1994 Toluene MR 3 SDWIS / IL0950450 / 2991
1994 Ethylbenzene MR 3 SDWIS / IL0950450 / 2992
1994 1,2,4-Trichlorobenzene MR 3 SDWIS / IL0950450 / 2378
1994 1,1,2-Trichloroethane MR 3 SDWIS / IL0950450 / 2985
1994 1,2-Dichloroethane MR 3 SDWIS / IL0950450 / 2980
1994 trans-1,2-Dichloroethylene MR 3 SDWIS / IL0950450 / 2979
1994 DICHLOROMETHANE MR 3 SDWIS / IL0950450 / 2964
1994 1,1-Dichloroethylene MR 3 SDWIS / IL0950450 / 2977

How Rio Compares

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

Metric Rio Illinois avg Federal benchmark
Total violations 165 69.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 15 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 265 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 Rio water safe to drink? ▼
Rio (PWS ID: IL0950450) has 165 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 265 people using Groundwater sources.
How many people does Rio serve? ▼
Rio serves 265 people in Rio, Illinois. It is a Local-owned system using Groundwater water sources with 106 service connections.
What type of violations does Rio have? ▼
Rio has 165 total violations: 15 health-based violations (MCL exceedances or treatment failures), 121 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Rio water? ▼
No PFAS testing data is available for Rio under the EPA's UCMR5 monitoring program.
What water source does Rio use? ▼
Rio 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.