City of Mercer Island
EPA ID: WA5353640 · 31,057 people served · 1 ZIP code
ZipCheckup's reading of EPA records for City of Mercer Island (WA5353640): no drinking-water violations recorded since 2021. City of Mercer Island has no EPA violations on record; the utility serves 31,057 residents.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Mercer Island Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: A
Demographics of ZIP Codes Served
The ZIP codes associated with City of Mercer Island have a median household income of $202,359 and about 25,282 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 67% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
City of Mercer Island'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.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in Washington
System Overview
City of Mercer Island (EPA ID: WA5353640) is a community water system in Washington that serves approximately 31,057 people from surface water sources.
This system serves ZIP code 98040 in Mercer Island.
ZIP-Area Home Safety Context: A (100/100)
This is the average Home Safety Score for 1 of 1 service-area ZIP codes with all required score domains observed. It is not a grade for the water utility.
Model 4.0.0 uses SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, the UCMR 5 PFAS MCL screen, EPA radon zone, and annual EPA AirData AQI across three equally weighted domains. Missing required evidence suppresses the score.
Violation History
Lead & Copper
No reported lead measurement appears for this PWSID in the accepted LCR snapshot. Absence of a reported measurement is not a measured zero.
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Radon Risk in Service Area
1 of 1 ZIP records with known zones is in EPA Radon Zone 3.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
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 WA or modeled from parcel and building-footprint data.
- 98040 - Mercer Island
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View available EPA compliance records for City of Mercer Island (WA5353640) on EPA.gov.
Frequently Asked Questions
Is City of Mercer Island water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for City of Mercer Island in the inclusive 2021-2026 record-year window. This is a compliance-record finding, not a guarantee about water at a specific tap.
How many people does City of Mercer Island serve?
City of Mercer Island serves approximately 31,057 people across 1 ZIP code in Washington.
Where does City of Mercer Island get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: No PFAS Reported Above Reporting Levels
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were reported above UCMR5 minimum reporting levels.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). City of Mercer Island, WA: Serves 31K People. https://zipcheckup.com/water-system/wa5353640/
@misc{zipcheckup-water-system-wa5353640,
author = {{ZipCheckup}},
title = {{City of Mercer Island, WA: Serves 31K People}},
year = {n.d.},
url = {https://zipcheckup.com/water-system/wa5353640/}
}