Willowbrook
EPA ID: IL0431100 · 9,000 people served · 5 ZIP codes
Current EPA status: Willowbrook, 2 open violations, 9,000 people served.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Worsening · Risk tier: High · 95% chance of violation in next 12 months
Violations went from 1 (2024) to 2 (2025). The pattern suggests growing compliance challenges.
Service Area Map
Coverage area for Willowbrook Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The Willowbrook serves a community with a median household income of $110,482 and an estimated 104,260 residents across its service area. Approximately 65% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Willowbrook's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in DuPage County, Illinois rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Wastewater Proximity Note: This service area ranks in the 66th percentile nationally for proximity to wastewater discharge points. Surface water sources near wastewater outfalls may face additional treatment challenges.
Superfund Proximity Note: This service area ranks in the 64th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How Willowbrook compares to EPA limits
What This Means For You
Total Trihalomethanes (TTHM) at 1 mg/L exceeds the EPA maximum of 0.08 mg/L. Bladder & rectal cancer risk; reproductive concerns. Consider granular activated carbon (GAC) filtration.
Surface Water Treatment Rule at 4 mg/L exceeds the EPA maximum of mg/L.
Stage 2 DBP Rule at 1 mg/L exceeds the EPA maximum of mg/L.
Total Trihalomethanes (TTHM) was detected in this water system. granular activated carbon (GAC) filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
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Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Willowbrook (EPA ID: IL0431100) is a community water system in Illinois that serves approximately 9,000 people from surface water sources.
This system provides water to 5 ZIP codes across 5 communities.
Average Home Safety Score: B (72/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 2, 2025 | Stage 2 DBP Rule | Monitoring | Unresolved |
| July 1, 2025 | Surface Water Treatment Rule | Monitoring | Unresolved |
| October 1, 2024 | Total Trihalomethanes (TTHM) | Monitoring | Resolved |
| July 1, 2023 | Surface Water Treatment Rule | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Surface Water Treatment Rule | Treatment Failure | 4 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 1 | No |
| Stage 2 DBP Rule | Treatment Failure | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 60527 | 0.0013 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by IL or modeled from parcel and building-footprint data.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Willowbrook (IL0431100) on EPA.gov.
Frequently Asked Questions
Is Willowbrook water safe to drink?
Willowbrook has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does Willowbrook serve?
Willowbrook serves approximately 9,000 people across 5 ZIP codes in Illinois.
Where does Willowbrook get its water?
The primary water source is surface water.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: WILLOWBROOK Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment classification and chemical list sourced from WILLOWBROOK Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Notable events and violations
This section summarizes events the utility chose to disclose in its most recent Consumer Confidence Report, plus any federal compliance violations the utility recorded against itself. Both lists are utility-authored — ZipCheckup does not audit, judge, or reorder them.
Federal compliance violations on record
These entries are taken verbatim from the utility's CCR violations section. EPA defines four broad violation categories: Maximum Contaminant Level (MCL), Treatment Technique (TT), Monitoring & Reporting (M&R), and Public Notification (PN).
-
reporting2022-07-01/2024-02-05
Failed to provide an annual report that adequately informed customers about water quality and risks.
-
reporting2023-07-01/2024-02-05
Failed to provide an annual report that adequately informed customers about water quality and risks.
-
monitoring · Haloacetic Acids (HAA5)2024-10-01/2024-12-31
Failed to test drinking water for Haloacetic Acids during the indicated period.
-
monitoring · Total Trihalomethanes (TTHM)2024-10-01/2024-12-31
Failed to test drinking water for Total Trihalomethanes during the indicated period.
Violations record from WILLOWBROOK Consumer Confidence Report.
ZipCheckup note: items above reflect what the utility published in its most recent CCR. Federal violation records are also tracked separately by the EPA Safe Drinking Water Information System (SDWIS) — the SDWIS record is the authoritative federal source for any specific regulatory action.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Willowbrook (EPA ID: IL0431100) — request the latest Consumer Confidence Report or ask about specific contaminants.