Arsenic in Sammamish, WA Drinking Water
Arsenic data for Sammamish, Washington · 88,043 residents · 2 ZIP codes
EPA records show Arsenic detections in Sammamish, Washington water samples.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14
Arsenic in Sammamish Tap Water
Arsenic has been detected in Sammamish, Washington drinking water at a maximum level of 6.6 ppb — below the EPA MCL of 10 ppb.
This analysis covers 88,043 residents across 2 ZIP codes in Sammamish.
Sammamish's overall water quality grade is A (88/100).
Is Arsenic in Sammamish Water Safe?
Arsenic was detected in Sammamish water but currently falls within EPA limits. However, some health organizations argue the EPA MCL may not be protective enough.
If you are concerned, a reverse osmosis filter can reduce arsenic levels further.
Arsenic Levels by ZIP Code
Average arsenic level across Sammamish: 6.6 ppb
Health Effects of Arsenic
- Increased risk of skin, bladder, lung, and kidney cancer
- Cardiovascular disease and type 2 diabetes
- Skin changes (darkening, thickening, lesions)
- Developmental effects in children exposed in utero
Health risk severity: High. Governed by the Arsenic Rule (2006).
How Arsenic Gets Into Drinking Water
- Natural deposits in rock and soil (especially in western U.S.)
- Runoff from orchards and glass/electronics production
- Historical use of arsenic-based pesticides
- Well water in areas with arsenic-rich geology
What to Do About Arsenic in Sammamish Water
- Install a reverse osmosis (RO) system certified under NSF 58
- Adsorptive media filters (iron-based) can also reduce arsenic
- Have well water tested if on a private supply
- Boiling water does NOT remove arsenic — it concentrates it
Look for filters certified under NSF 53 / NSF 58 for arsenic removal.