State distribution
Hardness across indexed ZIPs
Counts describe published ZIP profiles, not a population-weighted statewide sample.
Soft · 0–60 PPM22
Moderately hard · 61–120 PPM110
Hard · 121–180 PPM28
Very hard · 181+ PPM29
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 indexed hardness
104PPM
Moderately Hard
Indexed range 20.6–238 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 110 of 189 profiles with hardness data. The state median is 104 PPM, but the full indexed range is 20.6–238 PPM.
Evidence coverage
What the current records support
- Hardness estimate
- 100%
- Lead 90th percentile
- 90%
- Copper 90th percentile
- 35%
89
Low-confidence hardness profiles
69
Nearest site more than 25 miles away
Reported source water
Utility source mix
- Groundwater
- 85
- Surface water
- 45
- Groundwater influenced by surface water
- 3
Highest medians
Hardest indexed cities
- 1. Oroville238 PPM
- 2. Tonasket238 PPM
- 3. Chewelah217 PPM
- 4. Toppenish214 PPM
- 5. Harrah213 PPM
Lowest medians
Softest indexed cities
- 1. Long Beach21 PPM
- 2. South Bend22 PPM
- 3. Raymond24 PPM
- 4. Oak Harbor24 PPM
- 5. Chehalis24 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
57PPM
Single indexed valueNo active flag
Asotin
Asotin County · 1 ZIP
81PPM
Single indexed valueNo active flag
Auburn
King County · 3 ZIPs
106PPM
Single indexed valueNo active flag
Bainbridge Island
Kitsap County · 1 ZIP
106PPM
Single indexed valueNo active flag
Bellevue
King County · 5 ZIPs
61PPM
Single indexed valueNo active flag
Black Diamond
King County · 1 ZIP
104PPM
Single indexed valueNo active flag
Bothell
King County · 1 ZIP
61PPM
Single indexed valueNo active flag
Bremerton
Kitsap County · 4 ZIPs
61PPM
Single indexed valueNo active flag
Brewster
Okanogan County · 1 ZIP
191PPM
Single indexed valueNo active flag
Bridgeport
Douglas County · 1 ZIP
197PPM
Single indexed valueNo active flag
Buckley
Pierce County · 1 ZIP
61PPM
Single indexed valueNo active flag
Camas
Clark County · 1 ZIP
97PPM
Single indexed valueNo active flag
Carson
Skamania County · 1 ZIP
29PPM
Single indexed valueNo active flag
Cashmere
Chelan County · 1 ZIP
85PPM
Single indexed valueNo active flag
Castle Rock
Cowlitz County · 1 ZIP
37PPM
Single indexed valueNo active flag
Chehalis
Lewis County · 1 ZIP
24PPM
Single indexed valueNo active flag
Chelan
Chelan County · 1 ZIP
46PPM
Single indexed valueNo active flag
Cheney
Spokane County · 1 ZIP
138PPM
Single indexed valueNo active flag
Chewelah
Stevens County · 1 ZIP
217PPM
Single indexed valueNo active flag
Cle Elum
Kittitas County · 1 ZIP
111PPM
Single indexed valueNo active flag
Colfax
Whitman County · 1 ZIP
124PPM
Single indexed valueNo active flag
College Place
Walla Walla County · 1 ZIP
89PPM
Single indexed valueNo active flag
Colville
Stevens County · 1 ZIP
200PPM
Single indexed valueNo active flag
Connell
Franklin County · 1 ZIP
142PPM
Single indexed valueNo active flag
County comparison
Highest indexed county medians
| County | Median | Range | ZIP profiles |
|---|---|---|---|
| Stevens County | 209 PPM | 200–217 | 2 |
| Grant County | 202 PPM | 200–204 | 5 |
| Yakima County | 202 PPM | 85.7–214 | 12 |
| Douglas County | 199 PPM | 196.5–202 | 2 |
| Okanogan County | 188 PPM | 102.7–238 | 6 |
| Adams County | 188 PPM | 188–188.5 | 2 |
| Lincoln County | 160 PPM | 160–160 | 1 |
| Kittitas County | 157 PPM | 111–204 | 4 |
| Chelan County | 142 PPM | 46.1–204 | 5 |
| Spokane County | 134 PPM | 133–138 | 14 |
| Pend Oreille County | 134 PPM | 134–134 | 1 |
| Whitman County | 128 PPM | 115–133 | 4 |