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WaterSafeCheck

Mercer Island, WA Tap Water Quality

Water safety reports for all 1 ZIP code in Mercer Island, Washington

Average Score

87/100

Health Violations

0

ZIP Codes

1

High Lead Risk

1

of 1 ZIP codes

A

About Tap Water in Mercer Island, WA

Tap water in Mercer Island, WA ranks among the best in the state, maintaining a remarkable average water quality score of 87/100 across its 1 ZIP code. Based on recent EPA Safe Drinking Water Act compliance records, water provided by City of Mercer Island and other municipal suppliers has consistently met or exceeded federal safety standards. This top-tier "A" grade reflects strong infrastructure, diligent monitoring by Washington State Department of Health, and low contaminant levels.

A major factor in Mercer Island's high rating is its flawless health-based violation record. Over the past 5 years of EPA tracking, local water systems have recorded zero health-based violations. This means that regulated contaminants—such as lead, arsenic, and harmful bacteria—have not exceeded the Maximum Contaminant Levels (MCLs) allowed by federal law. Drawing primarily from surface water, the city utilizes advanced filtration to maintain this standard.

Additionally, lead exposure risk remains a critical issue for certain neighborhoods. EPA data indicates that 1 out of 1 ZIP codes in Mercer Island are rated as High or Very High risk for lead. This risk is often driven by aging homes with pre-1986 plumbing containing lead solder or service lines. Families in these areas should test their tap water and consider NSF/ANSI 53 certified filters.

⚠ Lead Risk Alert: Some ZIP codes in Mercer Island are rated High or Very High for lead exposure risk based on EPA data. Search your specific ZIP code for a detailed lead level report.

Water Quality by ZIP Code — Mercer Island, WA

Click any ZIP code for the full water quality report

A
98040

Mercer Island, WA

Score: 87/100✓ No violations

Frequently Asked Questions — Mercer Island Water Quality

Is tap water safe to drink in Mercer Island, WA?+
Yes — tap water in Mercer Island meets all federal EPA standards and earns a A grade. It is generally safe for healthy adults. As always, running your tap for 30 seconds before use and using a filter adds extra protection for vulnerable populations.
What is the water quality score for Mercer Island?+
The average water quality score across 1 ZIP code in Mercer Island, WA is 87/100. Scores are derived from EPA violation history, lead levels, enforcement actions, and infrastructure risk indicators. Individual ZIP codes may vary — search your specific ZIP above for a personalized report.
Does Mercer Island have lead in its tap water?+
1 out of 1 ZIP codes in Mercer Island are rated High or Very High for lead exposure risk. Older homes built before 1986 may have lead service lines or plumbing fixtures. Residents should run their tap for 30 seconds before use and consider a certified NSF/ANSI 53 lead filter.
How do I get the water quality report for Mercer Island?+
Each ZIP code in Mercer Island has a full water quality report on this site — click any ZIP code below. You can also get the annual Consumer Confidence Report (CCR) from your local water utility. The CCR is required to be published every year by July 1 and contains actual contaminant measurements and violation history.
Where does Mercer Island's tap water come from?+
Tap water in Mercer Island, WA primarily comes from surface water. Surface water systems treat water from rivers, lakes, or reservoirs using filtration, sedimentation, and disinfection before it reaches your tap.

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