Vashon Water Hardness & Quality Report (2026)
Water Hardness
3.6 grains per gallon
Source
reservoir
pH Level
7.6
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
146.4 mg/L
Est. Daily Cost
$0.17
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Vashon, your appliances are currently losing 8% efficiency due to mineral buildup.
| Appliance | In Vashon | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.6 yrs | 8.5 yrs | -11% |
| Washing Machine | 11.3 yrs | 12 yrs | -6% |
| Water Heater | 13.1 yrs | 15 yrs | -13% |
Regional Water Comparison
How Vashon compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Vashon, Washington | 62 mg/L | 2.8 ppt | 🟡 Moderately Hard | reservoir |
| Burien, Washington | 53.5 mg/L | 2.5 ppt | 🟢 Soft | reservoir |
| White Center, Washington | 23 mg/L | 1.6 ppt | 🟢 Soft | reservoir |
| Des Moines, Washington | 15 mg/L | 1.3 ppt | 🟢 Soft | reservoir |
| SeaTac, Washington | 70.5 mg/L | 3.1 ppt | 🟡 Moderately Hard | reservoir |
National Benchmark
How Vashon compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Vashon | 62 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Vashon's Water Unique?
Local geology and source profile
Vashon, Washington, in King County — a King County island community adjacent to Maury Island and the Kitsap Peninsula on Puget Sound — receives its water from the Vashon Sewer and Water District or King County, drawing from the Vashon Island groundwater through the Puget Sound island distribution.
The soft 62 mg/L hardness and TDS of 146.4 mg/L reflect the King County island supply's soft glacial till character — the Pleistocene Vashon Till and Quaternary Puget Glacial Drift are slightly calcareous glacially-deposited formations contributing moderate calcareous mineral content from their till deposits (compare Maury Island WA: 59/139 in King County comparable; Burien WA: 64/153 in King County comparable; Vashon consistent soft from the same King County Vashon Island Pleistocene glacial till supply). The Vashon Island groundwater — Pleistocene Vashon Till (slightly calcareous — primary hardness contributor), Quaternary Puget Glacial Drift (slightly calcareous — secondary contributor), and Holocene Puget Sound island alluvium (slightly calcareous — minor TDS).
At 62 mg/L with TDS 146, Vashon's water is soft — minimal scale buildup. Annual descaling is appropriate. The PFAS level of 2.8 ppt is low — a clean result for the Puget Sound islands. Review the Vashon Sewer and Water District's annual water quality report.
Geology & Source: Vashon in King County draws from the Vashon Water on the Vashon Island groundwater (King County, Puget Sound Washington) — the Puget Sound island draws from Pleistocene Vashon Till (slightly calcareous) and Quaternary Puget Glacial Drift (slightly calcareous) — Washington King County Vashon Island Pleistocene glacial till supply produces soft water at 62 mg/L with TDS 146.4 mg/L.