State distribution
Hardness across indexed ZIPs
Counts describe published ZIP profiles, not a population-weighted statewide sample.
Soft · 0–60 PPM15
Moderately hard · 61–120 PPM51
Hard · 121–180 PPM19
Very hard · 181+ PPM34
State water index
Washington water hardness
Search 133 indexed communities and 189 ZIP profiles, then compare the underlying utility, source, distance, and reporting context.
Median regional evidence
110PPM
Moderately Hard
Indexed range 29.6–1770 PPM
- ZIP profiles
- 189
- Cities
- 133
- Matched utilities
- 133
- Counties
- 34
Understanding Washington
Why local comparisons matter here
Washington combines Cascade snowmelt and large river systems with Puget Sound lowland aquifers and basalt or basin groundwater east of the mountains.
In this index, moderately hard is the largest category, covering 51 of 119 profiles with hardness data. The state median is 110 PPM, but the full indexed range is 29.6–1770 PPM.
Evidence coverage
What the current records support
- Hardness estimate
- 63%
- Lead 90th percentile
- 90%
- Copper 90th percentile
- 35%
84
Low-confidence hardness profiles
22
Research-comparison eligible profiles
Reported source water
Utility source mix
- Groundwater
- 85
- Surface water
- 45
- Groundwater influenced by surface water
- 3
Highest medians
Highest eligible city medians
- 1. Renton233 PPM
Lowest medians
Lowest eligible city medians
- 1. Renton233 PPM
City directory
Explore Washington by city
Search by city or county, then sort by name, hardness, or ZIP coverage.
133 cities · 189 ZIP profiles
133 cities found
Page 1 of 6
Aberdeen
Grays Harbor County · 1 ZIP
—
No regional sampleNo active flag
Asotin
Asotin County · 1 ZIP
115PPM regional
Single regional valueNo active flag
Auburn
King County · 3 ZIPs
55PPM regional
Regional range 53.7–232No active flag
Bainbridge Island
Kitsap County · 1 ZIP
233PPM regional
Single regional valueNo active flag
Bellevue
King County · 5 ZIPs
—
No regional sampleNo active flag
Black Diamond
King County · 1 ZIP
52PPM regional
Single regional valueNo active flag
Bothell
King County · 1 ZIP
—
No regional sampleNo active flag
Bremerton
Kitsap County · 4 ZIPs
—
No regional sampleNo active flag
Brewster
Okanogan County · 1 ZIP
276PPM regional
Single regional valueNo active flag
Bridgeport
Douglas County · 1 ZIP
257PPM regional
Single regional valueNo active flag
Buckley
Pierce County · 1 ZIP
99PPM regional
Single regional valueNo active flag
Camas
Clark County · 1 ZIP
—
No regional sampleNo active flag
Carson
Skamania County · 1 ZIP
—
No regional sampleNo active flag
Cashmere
Chelan County · 1 ZIP
—
No regional sampleNo active flag
Castle Rock
Cowlitz County · 1 ZIP
57PPM regional
Single regional valueNo active flag
Chehalis
Lewis County · 1 ZIP
—
No regional sampleNo active flag
Chelan
Chelan County · 1 ZIP
—
No regional sampleNo active flag
Cheney
Spokane County · 1 ZIP
134PPM regional
Single regional valueNo active flag
Chewelah
Stevens County · 1 ZIP
—
No regional sampleNo active flag
Cle Elum
Kittitas County · 1 ZIP
—
No regional sampleNo active flag
Colfax
Whitman County · 1 ZIP
112PPM regional
Single regional valueNo active flag
College Place
Walla Walla County · 1 ZIP
81PPM regional
Single regional valueNo active flag
Colville
Stevens County · 1 ZIP
—
No regional sampleNo active flag
Connell
Franklin County · 1 ZIP
183PPM regional
Single regional valueNo active flag
County comparison
Highest regional-evidence county medians
| County | Median | Range | ZIP profiles |
|---|---|---|---|
| Clallam County | 284 PPM | 284–284 | 3 |
| Okanogan County | 276 PPM | 47.1–276 | 6 |
| Kitsap County | 233 PPM | 232.5–1770 | 9 |
| Lincoln County | 217 PPM | 217–217 | 1 |
| Grant County | 206 PPM | 191–308.5 | 5 |
| Yakima County | 206 PPM | 111–288 | 12 |
| Kittitas County | 204 PPM | 204–204 | 4 |
| Douglas County | 200 PPM | 143–257 | 2 |
| Franklin County | 183 PPM | 183–183 | 2 |
| Adams County | 166 PPM | 135–196 | 2 |
| Spokane County | 158 PPM | 134–181 | 14 |
| Island County | 143 PPM | 142.5–142.5 | 2 |