TapSafetyReport
D35/100

Winthrop Harbor Tap Water Quality: Is It Safe to Drink? (2026 Report)

Serving 6,565 residents · Illinois

What's In Winthrop Harbor's Tap Water?

31
Contaminants Tested
0
Exceed EPA Limits
0
Above EPA Goals

EPA Violation History

17

Violations (last 5yr)

6

Unresolved

0

Health-Related

TIER 3Unresolved

Surface water treatment technique failure

When: July 1, 2025Enforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Resolved

Disinfection byproduct treatment technique failure

When: January 12, 2025 – January 22, 2025Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Disinfection byproduct treatment technique failure

When: October 11, 2024 – November 15, 2024Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Resolved

Disinfection byproduct treatment technique failure

When: October 11, 2024 – November 15, 2024Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Unresolved

Surface water treatment technique failure

When: July 1, 2024Enforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Resolved

Surface water treatment technique failure

When: July 1, 2024 – July 17, 2024Enforcement: 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: October 1, 2023 – December 31, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved

Failed to issue ongoing public notification

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: October 1, 2023 – February 23, 2024Rule: Ground Water 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: October 1, 2023 – December 31, 2023Rule: Stage 2 DBPREnforcement: 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 30, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Unresolved

Surface water treatment technique failure

When: July 1, 2023Enforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Resolved

Surface water treatment technique failure

When: July 1, 2023 – August 30, 2023Enforcement: 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 30, 2023Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Unresolved

Monitoring / Reporting Violation

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: December 30, 2022Rule: Ground Water RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Unresolved

Monitoring / Reporting Violation

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: December 30, 2021Rule: Ground Water RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Unresolved

Disinfection byproduct treatment technique failure

When: October 21, 2021Rule: Ground Water RuleEnforcement: Informal — resolved cooperativelyVerify on EPA.gov
TIER 3Resolved

Surface water treatment technique failure

When: July 1, 2021 – August 16, 2021Enforcement: 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

WINTHROP HARBOR
Population Served

6,565

Water Source

Purchased Surface Water

System ID

IL0971950

Frequently Asked Questions About Winthrop Harbor Water

Is Winthrop Harbor tap water safe to drink?

Winthrop Harbor, Illinois tap water receives a grade of D (35/100), which is considered poor. 0 contaminant(s) exceed EPA maximum contaminant levels and 37 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.

What contaminants are in Winthrop Harbor's water?

31 contaminants were tested in Winthrop Harbor's water supply. No contaminants exceed EPA legal limits (MCLs) or health goals (MCLGs), which is a positive indicator of water quality.

Does Winthrop Harbor have any water quality violations?

Yes, Winthrop Harbor has 37 EPA violation(s) on record, with the most recent in 2025. Violation types include Other, MR, MCL. 7 of these are health-based violations, which are the most serious category.

Do I need a water filter in Winthrop Harbor?

Winthrop Harbor 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 Winthrop Harbor's tap water come from?

Winthrop Harbor's drinking water is sourced from purchased surface water and supplied by WINTHROP HARBOR. The system serves approximately 6,565 people. Surface water sources include rivers, lakes, and reservoirs.

How often is Winthrop Harbor'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. Winthrop Harbor'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 Winthrop Harbor's water compare to other cities in Illinois?

Winthrop Harbor's water quality score of 35/100 earns a grade of D, which is considered poor. This is a concerning score that suggests significant water quality issues. Visit our Illinois state page to see how all cities in the state compare.

What should I do if I'm concerned about Winthrop Harbor's water quality?

If you have concerns about Winthrop Harbor'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 (WINTHROP HARBOR) 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.

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