SAMMAMISH PLATEAU WATER & SEWER
High Risk2 PFAS compound(s) exceed EPA Maximum Contaminant Levels
This utility has until 2029 to install treatment under the EPA's April 2024 PFAS rule. In the meantime, a point-of-use filter certified NSF/ANSI 58 for PFOA/PFOS provides reliable interim protection.
6
PFAS Detected
2
Above EPA Limits
4
ZIPs Served
Groundwater
Water Source
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOS Perfluorooctane sulfonic acid | 11.10ppt | 278% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 16.50ppt | 165% of limit
| 10 ppt | ⚠ Exceeds MCL |
PFBS Perfluorobutane sulfonic acid | 8.80ppt | No federal limit | — | Unregulated |
PFHxA Perfluorohexanoic acid | 4.30ppt | No federal limit | — | Unregulated |
PFPeS | 4.10ppt | No federal limit | — | Unregulated |
PFPeA Perfluoropentanoic acid | 3.90ppt | No federal limit | — | Unregulated |
ZIP Codes Served by This Utility
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About this data
Source
EPA UCMR 5 — January 2026 release
Sampling period
January 2023 – December 2025
Water system ID (PWSID)
WA5340900
Detection threshold (MRL)
~1.5–2 ppt — "Not detected" means below this floor