- EPA's UCMR 5 testing looked for 30 contaminants here and found 6.
- PFHxS (a PFAS): found in 9 of 16 samples, average 4 ppt, highest 16.5 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFBS (a PFAS): found in 6 of 16 samples, average 2.1 ppt, highest 8.8 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFOS (a PFAS): found in 4 of 16 samples, average 1.7 ppt, highest 11.1 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFHxA (a PFAS): found in 2 of 16 samples, average 0.50 ppt, highest 4.3 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFPeA (a PFAS): found in 2 of 16 samples, average 0.40 ppt, highest 3.9 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- PFPeS (a PFAS): found in 1 of 16 samples, average 0.30 ppt, highest 4.1 ppt (EPA UCMR 5 testing, May 2023–Feb 2024)
- Lead, 90th percentile: 1.7 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
Public EPA test results
Can you drink Sammamish tap water? What EPA records show
EPA WA5340900 · serves King County, WA · about 79,362 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
Sammamish Plateau Water & Sewer (EPA WA5340900)
EPA data as of October 14, 2026. For Sammamish's main utility, Sammamish Plateau Water & Sewer: We found no health-based violations in EPA's records for this system (WA5340900) since July 1, 2021, as of October 14, 2026. EPA's UCMR 5 testing looked for 30 contaminants here and found 6. This is public data, not a test of your tap.
What EPA records show for Sammamish Plateau Water & Sewer, as of October 14, 2026
We found no health-based violations in EPA's records for this system (WA5340900) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Sammamish Plateau Water & Sewer (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 1.7 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 6.
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 Sammamish Plateau Water & Sewer use chloramine?
We didn't find chloramine in Sammamish Plateau Water & Sewer's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.