A83/100
NORTHBROOK — Water Quality Report 2026
Serving 34,407 people · Illinois
Water Source
Surface Water
County
—
System ID
IL0312070
Violations
5
Contaminant Test Results
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Lead (90th percentile) | 0.016 mg/L | 0.015 mg/L | Over Limit |
EPA Violation History
1
Violation (last 5yr)
0
Unresolved
0
Health-Related
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 30, 2023Rule: Stage 2 DBPREnforcement: 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
Frequently Asked Questions About NORTHBROOK
Is NORTHBROOK water safe to drink?
NORTHBROOK water receives a grade of A (83/100), which is considered excellent. Out of 69 contaminants tested, 1 exceed EPA legal limits. 1 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.
What contaminants has NORTHBROOK detected?
69 contaminants were tested in NORTHBROOK's water. Notable contaminants include Lead (90th percentile). 1 exceed EPA legal limits (MCLs). 1 exceed EPA health goals (MCLGs).
Does NORTHBROOK have any EPA violations?
Yes, NORTHBROOK has 5 EPA violation(s) on record, with the most recent in 2023. Violation types include MR, TT. 1 are health-based violations.
How many people does NORTHBROOK serve?
NORTHBROOK serves approximately 34,407 people, Illinois. The system provides water to 1 community: Northbrook.
What type of water does NORTHBROOK provide?
NORTHBROOK sources its water from surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is IL0312070.
How does NORTHBROOK compare to other utilities in Illinois?
NORTHBROOK scores 83/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our Illinois state page for a full comparison of water systems.