- EPA's UCMR 5 testing looked for 30 contaminants here and found none.
Public EPA test results
Can you drink Mercer Island tap water? What EPA records show
EPA WA5353640 · serves King County, WA · about 31,057 people (EPA SDWIS)
This report shows EPA's federal records for this water system: UCMR 5 testing, lead testing and violations. It isn't a test of the water at your tap, and it has no Water Score.
Public EPA test results
Mercer Island City of (EPA WA5353640)
EPA data as of October 14, 2026. For Mercer Island's main utility, Mercer Island City of: We found no health-based violations in EPA's records for this system (WA5353640) since July 1, 2021, as of October 14, 2026. PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
What EPA records show for Mercer Island City of, as of October 14, 2026
We found no health-based violations in EPA's records for this system (WA5353640) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Mercer Island City of (SDWIS). Data as of October 14, 2026.
This system buys water from Seattle Public Utilities (WA5377050); see that system's records.
Source: Seattle Public Utilities (WA5377050) report. Data as of October 14, 2026.
EPA's UCMR 5 testing looked for 30 contaminants here and found none.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Mercer Island City of use chloramine?
We didn't find chloramine in Mercer Island City of's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.