A91/100
Oak Forest Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 27,478 residents · Illinois
What's In Oak Forest's Tap Water?
69
Contaminants Tested
0
Exceed EPA Limits
0
Above EPA Goals
EPA Violation History
2
Violations (last 5yr)
2
Unresolved
0
Health-Related
TIER 3Unresolved
Reporting Violation
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: July 2, 2025Rule: Ground Water RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Unresolved
Surface water treatment technique failure
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
OAK FOREST
Population Served
27,478
Water Source
Purchased Surface Water
System ID
IL0312190
Frequently Asked Questions About Oak Forest Water
Is Oak Forest tap water safe to drink?
Oak Forest, Illinois tap water receives a grade of A (91/100), which is considered excellent. Out of 69 contaminants tested, none exceed EPA maximum contaminant levels (MCLs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Oak Forest's water?
69 contaminants were tested in Oak Forest's water supply. No contaminants exceed EPA legal limits (MCLs) or health goals (MCLGs), which is a positive indicator of water quality.
Does Oak Forest have any water quality violations?
Yes, Oak Forest has 9 EPA violation(s) on record, with the most recent in 2025. Violation types include RPT, Other, MR. None of these are classified as health-based violations.
Do I need a water filter in Oak Forest?
Oak Forest water meets EPA standards, so a filter is not strictly necessary. However, some residents prefer the added security of a water filter. EPA health goals (MCLGs) are stricter than legal limits and are set at levels with zero expected health risk. All contaminants are within health goals.
Where does Oak Forest's tap water come from?
Oak Forest's drinking water is sourced from purchased surface water and supplied by OAK FOREST. The system serves approximately 27,478 people. Surface water sources include rivers, lakes, and reservoirs.
How often is Oak Forest'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. Oak Forest'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 Oak Forest's water compare to other cities in Illinois?
Oak Forest's water quality score of 91/100 earns a grade of A, which is considered excellent. This places Oak Forest among the better-performing water systems in Illinois. Visit our Illinois state page to see how all cities in the state compare.
What should I do if I'm concerned about Oak Forest's water quality?
If you have concerns about Oak Forest'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 (OAK FOREST) 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.