A92/100
MERCER ISLAND CITY OF — Water Quality Report 2026
Serving 30,689 people · Washington
Water Source
Purchased Surface Water
County
—
System ID
WA5353640
Violations
4
Contaminant Test Results
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 1992.
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 MERCER ISLAND CITY OF
Is MERCER ISLAND CITY OF water safe to drink?
MERCER ISLAND CITY OF water receives a grade of A (92/100), which is considered excellent. Out of 68 contaminants tested, none exceed EPA legal limits. The water meets federal safety standards.
What contaminants has MERCER ISLAND CITY OF detected?
68 contaminants were tested in MERCER ISLAND CITY OF's water. No contaminants exceed EPA legal limits or health goals, indicating good water quality management.
Does MERCER ISLAND CITY OF have any EPA violations?
Yes, MERCER ISLAND CITY OF has 4 EPA violation(s) on record, with the most recent in 1992. Violation types include MR, MCL. 1 are health-based violations.
How many people does MERCER ISLAND CITY OF serve?
MERCER ISLAND CITY OF serves approximately 30,689 people, Washington.
What type of water does MERCER ISLAND CITY OF provide?
MERCER ISLAND CITY OF sources its water from purchased surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is WA5353640.
How does MERCER ISLAND CITY OF compare to other utilities in Washington?
MERCER ISLAND CITY OF scores 92/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our Washington state page for a full comparison of water systems.