Mercer Island, Washington: Is the Tap Water Safe to Drink?
2026 EPA water quality data for 2 community water systems serving 31,153+ residents. See violations, PFAS results, lead test results, and safety grades — free.
Is Mercer Island Tap Water Safe to Drink?
Based on the latest EPA data, Mercer Island tap water meets all federal drinking water standards. All 2 tested systems have received a safety grade of A or B, with no active health-based violations.
Mercer Island Water Quality Overview
Mercer Island, Washington is served by 2 community water systems providing water to approximately 31,153 residents. These systems draw from surface water purchased (1), groundwater (1) sources. Mercer Island water systems have no recorded health-based violations. Including monitoring and reporting violations, there are 1 total violation on record.
Find Your Water System
Search by ZIP code to find your exact water provider and see its full EPA report.
All 2 water systems in Mercer Island
Looking for water quality data across the whole state? See our full Washington tap water safety report covering Washington’s EPA-regulated water systems.
Mercer Island Drinking Water: Frequently Asked Questions
Is Mercer Island, Washington tap water safe to drink?
Based on the latest EPA data, Mercer Island tap water meets all federal drinking water standards. All 2 tested systems have received a safety grade of A or B, with no active health-based violations.
How many water utilities serve Mercer Island, Washington?
2 community water systems serve Mercer Island, Washington, providing water to approximately 31,153 people. Different neighborhoods may be served by different utilities. Enter your ZIP code at the top to find your specific provider.
Does Mercer Island tap water have lead?
Lead in drinking water typically enters from old pipes and fixtures inside homes and buildings, not from the treatment plant. The EPA requires water systems to monitor for lead under the Lead and Copper Rule. Click any water system above to see its most recent 90th-percentile lead test results. Homes built before 1986 are most likely to have lead plumbing components.
What contaminants have been found in Mercer Island drinking water?
EPA violation records for Mercer Island water systems are listed on each utility's report page. Common regulated contaminants include disinfection byproducts (TTHMs, HAA5), coliform bacteria, nitrates, and lead. Click any utility above to see its full violation history going back 10 years.
How do I find out which water company serves my address in Mercer Island?
Enter your Mercer Island ZIP code in the search box at the top of this page. ClearWater will identify the specific water system serving your area and show you its EPA violation history, lead test results, and an overall safety grade. You can also check your water bill or your utility's annual Consumer Confidence Report (CCR).