B79/100
Onarga Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 1,409 residents · Illinois
What's In Onarga's Tap Water?
2
Contaminants Tested
1
Exceed EPA Limits
0
Above EPA Goals
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.40 mg/L | 1.30 mg/L | Over Limit |
EPA Violation History
5
Violations (last 5yr)
0
Unresolved
0
Health-Related
TIER 3Resolved
Disinfection byproduct treatment technique failure
When: October 16, 2024 – December 3, 2024Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved
Disinfection byproduct treatment technique failure
When: October 16, 2024 – December 3, 2024Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved
Monitoring Violation
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: August 1, 2023 – August 31, 2023Rule: Total Coliform RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: July 1, 2023 – September 25, 2023Rule: Stage 1 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved
Consumer confidence report — inadequate or unavailable
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: July 1, 2021 – February 15, 2022Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
ONARGA
Population Served
1,409
Water Source
Groundwater
System ID
IL0750700
Frequently Asked Questions About Onarga Water
Is Onarga tap water safe to drink?
Onarga, Illinois tap water receives a grade of B (79/100), which is considered good. Out of 2 contaminants tested, 1 exceed EPA maximum contaminant levels (MCLs) and 1 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Onarga's water?
Of the 2 contaminants tested in Onarga's water supply, the most notable include Copper (90th percentile). 1 contaminant(s) exceed EPA legal limits (MCLs). 1 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Onarga have any water quality violations?
Yes, Onarga has 9 EPA violation(s) on record, with the most recent in 2024. Violation types include Other, MON, MR. 1 of these are health-based violations, which are the most serious category.
Do I need a water filter in Onarga?
Based on EPA data, using a water filter in Onarga is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Onarga's tap water come from?
Onarga's drinking water is sourced from groundwater and supplied by ONARGA. The system serves approximately 1,409 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.
How often is Onarga's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Onarga's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Onarga's water compare to other cities in Illinois?
Onarga's water quality score of 79/100 earns a grade of B, which is considered good. This is an above-average score compared to many cities nationwide. Visit our Illinois state page to see how all cities in the state compare.
What should I do if I'm concerned about Onarga's water quality?
If you have concerns about Onarga's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (ONARGA) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.