How does Vashon's water compare to the national average?

The USA national average is 151 mg/L. Vashon (62 mg/L) is 89 mg/L softer than average.

Vashon Water Hardness & Quality Report (2026)

Water Hardness

62mg/L

Moderately Hard

3.6 grains per gallon

Source

reservoir

pH Level

7.4

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: See methodology section below · Updated 2026

62mg/L as CaCO₃Moderately Hard

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	7.8 yrs	8.5 yrs	-8%
Washing Machine	11 yrs	12 yrs	-8%
Water Heater	13.8 yrs	15 yrs	-8%

Regional Water Comparison

How Vashon compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Vashon, Washington	62 mg/L	0 ppt	🟡 Moderately Hard	reservoir
Burien, Washington	≈ 0–60 mg/L	0 ppt	🟢 Soft	reservoir
White Center, Washington	≈ 0–60 mg/L	1.6 ppt	🟢 Soft	reservoir
Des Moines, Washington	≈ 0–60 mg/L	0 ppt	🟢 Soft	reservoir
SeaTac, Washington	≈ 0–60 mg/L	3.1 ppt	🟢 Soft	reservoir

National Benchmark

How Vashon compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Vashon	62 mg/L	🟡 Low
USA National Avg	151 mg/L	🟠 Moderate
Scarsdale Top Rated	0.02 mg/L	🟢 None

Bring Scarsdale-quality water to your Vashon home

Shop water softeners on Amazon.com →

Shop Now

What Makes Vashon's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 146.4 mg/LpH: 7.4

Water District 19 provides drinking water to about 3,723 people on Vashon-Maury Island, King County, Washington. This utility manages a groundwater system, pulling water from local aquifers that lie beneath the island. Based on King County monitoring data from 2023, the water supplied to the Vashon-Maury Island community meets primary drinking water standards for most tested elements. The system draws from aquifers formed within glacial deposits and the underlying Tertiary bedrock, characteristic of the Puget Sound region.

Water on Vashon-Maury Island comes from aquifers within glacial deposits resting on Tertiary bedrock. This island geology is shaped by post-glacial activity and mineral-rich formations. While specific aquifer names or geological periods weren't detailed, the groundwater naturally contains arsenic in some wells, a common trait in the Pacific Northwest's post-glacial geological landscape. This natural presence of minerals influences the water's composition.

While the public water system meets standards, some residents drawing from private wells in this region should be aware of naturally occurring arsenic. Although Water District 19's system reported no arsenic levels exceeding EPA standards, the presence of this element in local groundwater is a known factor. The water's hardness wasn't specified, but the island's glacial geology typically suggests moderate mineralization. For the most current and detailed compliance information, residents should always refer to Water District 19's annual Consumer Confidence Report.

Geology & Source: Glacial deposits over Tertiary bedrock; groundwater shows natural arsenic occurrence from mineral-bearing formations

Other Washington Water Reports

Burien

≈ 0–60 mg/L

🟢 Soft

White Center

≈ 0–60 mg/L

🟢 Soft

Des Moines

≈ 0–60 mg/L

🟢 Soft

SeaTac

≈ 0–60 mg/L

🟢 Soft

Report an Issue

Notice an error or missing data? Help us keep this page accurate. If you spot incorrect water hardness, outdated utility info, or missing details, please let us know.

All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is Vashon's water safe to drink?

Yes. Vashon's water meets all federal safety standards. The hardness is 62 mg/L (Moderately Hard), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Vashon?

Vashon's water is moderately hard at 62 mg/L. A water softener is generally not necessary, though a carbon filter can improve taste and remove any remaining chlorine.

How does Vashon compare to the USA average?

The USA national average is 151 mg/L. Vashon (62 mg/L) is 89 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Vashon is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

Water Hardness

Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

TDS — Total Dissolved Solids

Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.

Measured

PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances

EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.

Modelled

Lead

Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.

Calculated

Appliance Lifespan

Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.