Water Hardness in Washington
Across 227 measured cities — with 159 more covered by labeled county-level estimates — Washington's median tap water hardness is 41.4 mg/L (2.4 gpg): soft on the USGS scale. Below: every covered city, the state's hardest and softest water, and the geology that explains it.
Data updated July 6, 2026. Sources: utility-reported water quality data and USGS/EPA Water Quality Portal samples.
State Median
41.4
mg/L (2.4 gpg), measured cities
Measured Range
12.6-289.1
mg/L across measured cities
Measured Cities
227
utility-reported or computed values
County Estimates
159
41% of covered cities
Washington Cities by Hardness Category
Measured cities only — labeled county estimates never enter the category counts or the median.
| Category | Range | Measured cities | Share |
|---|---|---|---|
| Soft | 0-60 mg/L | 148 | 65.2% |
| Moderately hard | 60-120 mg/L | 58 | 25.6% |
| Hard | 120-180 mg/L | 15 | 6.6% |
| Very hard | >180 mg/L | 6 | 2.6% |
Hardest and Softest Water in Washington
Measured values only; labeled county estimates and values under active dispute never rank.
Hardest water in Washington
Softest water in Washington
- Alderwood Manor — 12.6 mg/L (0.7 gpg), soft
- Bothell East — 12.6 mg/L (0.7 gpg), soft
- Bothell West — 12.6 mg/L (0.7 gpg), soft
- Brier — 12.6 mg/L (0.7 gpg), soft
- Lake Stickney — 12.6 mg/L (0.7 gpg), soft
Every Covered City in Washington
All 386 covered Washington cities, sorted by population served. "County estimate" rows are labeled context values from USGS/EPA Water Quality Portal county sampling — they never enter the median above. City names link to each city's full water quality page.
| City | Hardness (mg/L) | gpg | Category | Data |
|---|---|---|---|---|
| Tukwila | 36.6 | 2.1 | Soft | Utility-reported |
| Lake Forest Park | 30.3 | 1.8 | Soft | Utility-reported |
| Bryn Mawr-Skyway | 34.8 | 2.0 | Soft | Utility-reported |
| Burien | 33.2 | 1.9 | Soft | Utility-reported |
| Boulevard Park | 30.9 | 1.8 | Soft | Utility-reported |
| White Center | 30.9 | 1.8 | Soft | Utility-reported |
| Shoreline | 30.8 | 1.8 | Soft | Utility-reported |
| Seattle | 30.9 | 1.8 | Soft | Utility-reported |
| Federal Way | 31.4 | 1.8 | Soft | Utility-reported |
| Five Corners | 100.6 | 5.9 | Moderately hard | Utility-reported |
| Hazel Dell | 100.6 | 5.9 | Moderately hard | Utility-reported |
| Hockinson | 100.6 | 5.9 | Moderately hard | Utility-reported |
| Orchards | 100.6 | 5.9 | Moderately hard | Utility-reported |
| Redmond | 39.2 | 2.3 | Soft | Utility-reported |
| Vancouver | 99.8 | 5.8 | Moderately hard | Utility-reported |
| Bothell | 19.2 | 1.1 | Soft | Utility-reported |
| Frederickson | 21.8 | 1.3 | Soft | Utility-reported |
| Parkland | 21.8 | 1.3 | Soft | Utility-reported |
| Minnehaha | 105.0 | 6.1 | Moderately hard | Utility-reported |
| Alderton | 29.1 | 1.7 | Soft | Utility-reported |
| Issaquah | 40.9 | 2.4 | Soft | Utility-reported |
| Clover Creek | 21.8 | 1.3 | Soft | Utility-reported |
| Midland | 21.8 | 1.3 | Soft | Utility-reported |
| Spokane Valley | 131.0 | 7.7 | Hard | Utility-reported |
| Bonney Lake | 29.7 | 1.7 | Soft | Utility-reported |
| Prairie Ridge | 29.7 | 1.7 | Soft | Utility-reported |
| Puyallup | 29.1 | 1.7 | Soft | Utility-reported |
| Kirkland | 34.2 | 2.0 | Soft | Utility-reported |
| Graham | 21.8 | 1.3 | Soft | Utility-reported |
| South Hill | 21.8 | 1.3 | Soft | Utility-reported |
| Summit | 21.8 | 1.3 | Soft | Utility-reported |
| Summit View | 21.8 | 1.3 | Soft | Utility-reported |
| Waller | 21.8 | 1.3 | Soft | Utility-reported |
| Orting | 21.8 | 1.3 | Soft | Utility-reported |
| Tehaleh | 21.8 | 1.3 | Soft | Utility-reported |
| Fircrest | 21.8 | 1.3 | Soft | Utility-reported |
| Fife Heights | 21.8 | 1.3 | Soft | Utility-reported |
| Prairie Heights | 21.8 | 1.3 | Soft | Utility-reported |
| Yarrow Point | 32.2 | 1.9 | Soft | Utility-reported |
| Tacoma | 21.8 | 1.3 | Soft | Utility-reported |
| Auburn | 57.5 | 3.4 | Soft | Utility-reported |
| Browns Point | 21.8 | 1.3 | Soft | Utility-reported |
| Dash Point | 21.8 | 1.3 | Soft | Utility-reported |
| McMillin | 21.8 | 1.3 | Soft | Utility-reported |
| Ruston | 21.8 | 1.3 | Soft | Utility-reported |
| University Place | 21.8 | 1.3 | Soft | Utility-reported |
| Kent | 52.5 | 3.1 | Soft | Utility-reported |
| Bellevue | 34.5 | 2.0 | Soft | Utility-reported |
| Town and Country | 130.3 | 7.6 | Hard | Utility-reported |
| Beaux Arts Village | 34.9 | 2.0 | Soft | Utility-reported |
| Clyde Hill | 34.9 | 2.0 | Soft | Utility-reported |
| Hunts Point | 34.9 | 2.0 | Soft | Utility-reported |
| Medina | 34.9 | 2.0 | Soft | Utility-reported |
| Union Hill-Novelty Hill | 49.5 | 2.9 | Soft | Utility-reported |
| Lynnwood | 15.4 | 0.9 | Soft | Utility-reported |
| Airway Heights | 131.0 | 7.7 | Hard | Utility-reported |
| Spokane | 131.0 | 7.7 | Hard | Utility-reported |
| Four Lakes | 131.0 | 7.7 | Hard | Utility-reported |
| Renton | 49.0 | 2.9 | Soft | Utility-reported |
| Mukilteo | 12.6 | 0.7 | Soft | Utility-reported |
| Clearview | 15.8 | 0.9 | Soft | Utility-reported |
| Maltby | 15.8 | 0.9 | Soft | Utility-reported |
| Bothell West | 12.6 | 0.7 | Soft | Utility-reported |
| Mill Creek | 12.6 | 0.7 | Soft | Utility-reported |
| Mill Creek East | 12.6 | 0.7 | Soft | Utility-reported |
| Alderwood Manor | 12.6 | 0.7 | Soft | Utility-reported |
| Bothell East | 12.6 | 0.7 | Soft | Utility-reported |
| Brier | 12.6 | 0.7 | Soft | Utility-reported |
| Lake Stickney | 12.6 | 0.7 | Soft | Utility-reported |
| Larch Way | 12.6 | 0.7 | Soft | Utility-reported |
| Martha Lake | 12.6 | 0.7 | Soft | Utility-reported |
| Meadowdale | 12.6 | 0.7 | Soft | Utility-reported |
| North Lynnwood | 12.6 | 0.7 | Soft | Utility-reported |
| Picnic Point | 12.6 | 0.7 | Soft | Utility-reported |
| Des Moines | 47.8 | 2.8 | Soft | Utility-reported |
| Lakeland North | 47.8 | 2.8 | Soft | Utility-reported |
| Everett | 18.9 | 1.1 | Soft | Utility-reported |
| Eastmont | 22.2 | 1.3 | Soft | Utility-reported |
| Tanglewilde | 83.0 | 4.8 | Moderately hard | Utility-reported |
| Sisco Heights | 35.8 | 2.1 | Soft | Utility-reported |
| SeaTac | 64.1 | 3.8 | Moderately hard | Utility-reported |
| Fern Prairie | 75.5 | 4.4 | Moderately hard | Utility-reported |
| Battle Ground | 85.3 | 5.0 | Moderately hard | Utility-reported |
| Cherry Grove | 85.3 | 5.0 | Moderately hard | Utility-reported |
| Lewisville | 85.3 | 5.0 | Moderately hard | Utility-reported |
| Venersborg | 85.3 | 5.0 | Moderately hard | Utility-reported |
| Lake Cassidy | 35.8 | 2.1 | Soft | Utility-reported |
| Ridgefield | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Port Orchard | 38.9 | 2.3 | Soft | Utility-reported |
| Milton | 37.9 | 2.2 | Soft | Utility-reported |
| Pacific | 38.9 | 2.3 | Soft | Utility-reported |
| Woodland | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Fairwood | 53.3 | 3.1 | Soft | Utility-reported |
| Lakeland South | 37.9 | 2.2 | Soft | Utility-reported |
| Lake Morton-Berrydale | 52.1 | 3.0 | Soft | Utility-reported |
| Amboy | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Barberton | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Brush Prairie | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Dollars Corner | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Duluth | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Felida | 85.9 | 5.0 | Moderately hard | Utility-reported |
| La Center | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Lake Shore | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Meadow Glade | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Mount Vista | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Salmon Creek | 85.9 | 5.0 | Moderately hard | Utility-reported |
| Yakima | 38.6 | 2.3 | Soft | Computed from Ca+Mg |
| Kenmore | 25.1 | 1.5 | Soft | Utility-reported |
| Bellingham | 29.2 | 1.7 | Soft | Utility-reported |
| Marietta-Alderwood | 29.2 | 1.7 | Soft | Utility-reported |
| Camas | 59.9 | 3.5 | Soft | Utility-reported |
| Enetai | 48.9 | 2.9 | Soft | Utility-reported |
| Tracyton | 48.9 | 2.9 | Soft | Utility-reported |
| Lakewood | 72.4 | 4.2 | Moderately hard | Utility-reported |
| Maple Heights-Lake Desire | 23.8 | 1.4 | Soft | Utility-reported |
| Arlington | 28.6 | 1.7 | Soft | County estimate |
| Normandy Park | 64.1 | 3.8 | Moderately hard | Utility-reported |
| Lacey | 110.0 | 6.4 | Moderately hard | Utility-reported |
| Bremerton | 38.9 | 2.3 | Soft | Utility-reported |
| Kennewick | 96.1 | 5.6 | Moderately hard | Utility-reported |
| Finley | 96.1 | 5.6 | Moderately hard | Utility-reported |
| Olympia | 52.0 | 3.0 | Soft | Utility-reported |
| Pasco | 268.5 | 15.7 | Very hard | County estimate |
| Mount Vernon | 18.1 | 1.1 | Soft | Utility-reported |
| Clear Lake | 18.1 | 1.1 | Soft | Utility-reported |
| DuPont | 39.3 | 2.3 | Soft | County estimate |
| Alger | 18.1 | 1.1 | Soft | Utility-reported |
| Bay View | 18.1 | 1.1 | Soft | Utility-reported |
| Big Lake | 18.1 | 1.1 | Soft | Utility-reported |
| Burlington | 18.1 | 1.1 | Soft | Utility-reported |
| Sedro-Woolley | 18.1 | 1.1 | Soft | Utility-reported |
| Union Gap | 30.6 | 1.8 | Soft | Computed from Ca+Mg |
| Maple Valley | 45.9 | 2.7 | Soft | Utility-reported |
| Shadow Lake | 45.9 | 2.7 | Soft | Utility-reported |
| Kitsap Lake | 38.9 | 2.3 | Soft | Utility-reported |
| Sammamish | 62.4 | 3.6 | Moderately hard | Utility-reported |
| Rocky Point | 38.9 | 2.3 | Soft | Utility-reported |
| Covington | 59.2 | 3.5 | Soft | Utility-reported |
| Marysville | 28.6 | 1.7 | Soft | County estimate |
| Gleed | 30.6 | 1.8 | Soft | Computed from Ca+Mg |
| Gorst | 38.9 | 2.3 | Soft | Utility-reported |
| Navy Yard City | 38.9 | 2.3 | Soft | Utility-reported |
| Snohomish | 35.8 | 2.1 | Soft | Utility-reported |
| Steilacoom | 72.4 | 4.2 | Moderately hard | Utility-reported |
| Ames Lake | 62.6 | 3.7 | Moderately hard | Utility-reported |
| Three Lakes | 35.8 | 2.1 | Soft | Utility-reported |
| Chain Lake | 35.8 | 2.1 | Soft | Utility-reported |
| Richland | 89.3 | 5.2 | Moderately hard | Utility-reported |
| Tumwater | 60.2 | 3.5 | Moderately hard | Utility-reported |
| Longview | 127.0 | 7.4 | Hard | Utility-reported |
| Spanaway | 39.3 | 2.3 | Soft | County estimate |
| Longview Heights | 127.0 | 7.4 | Hard | Utility-reported |
| Woodinville | 25.3 | 1.5 | Soft | Utility-reported |
| Cottage Lake | 25.3 | 1.5 | Soft | Utility-reported |
| Lochsloy | 35.8 | 2.1 | Soft | Utility-reported |
| Arlington Heights | 35.8 | 2.1 | Soft | Utility-reported |
| Bunk Foss | 35.8 | 2.1 | Soft | Utility-reported |
| Canyon Creek | 35.8 | 2.1 | Soft | Utility-reported |
| Cavalero | 35.8 | 2.1 | Soft | Utility-reported |
| Granite Falls | 35.8 | 2.1 | Soft | Utility-reported |
| Lake Bosworth | 35.8 | 2.1 | Soft | Utility-reported |
| Lake Roesiger | 35.8 | 2.1 | Soft | Utility-reported |
| Lake Stevens | 35.8 | 2.1 | Soft | Utility-reported |
| Machias | 35.8 | 2.1 | Soft | Utility-reported |
| Edmonds | 35.3 | 2.1 | Soft | Utility-reported |
| Pullman | 115.0 | 6.7 | Moderately hard | Computed from Ca+Mg |
| McChord AFB | 39.3 | 2.3 | Soft | County estimate |
| Roy | 39.3 | 2.3 | Soft | County estimate |
| Washougal | 40.2 | 2.4 | Soft | Utility-reported |
| Black Diamond | 45.9 | 2.7 | Soft | Utility-reported |
| North Puyallup | 93.2 | 5.5 | Moderately hard | Utility-reported |
| Lake Holm | 45.9 | 2.7 | Soft | Utility-reported |
| Ravensdale | 45.9 | 2.7 | Soft | Utility-reported |
| Silverdale | 79.8 | 4.7 | Moderately hard | Utility-reported |
| South Wenatchee | 80.3 | 4.7 | Moderately hard | Utility-reported |
| Wenatchee | 80.3 | 4.7 | Moderately hard | Utility-reported |
| Oak Harbor | 44.8 | 2.6 | Soft | Utility-reported |
| East Wenatchee | 80.0 | 4.7 | Moderately hard | Utility-reported |
| Liberty Lake | 22.9 | 1.3 | Soft | County estimate |
| Chehalis | 2.4 | 0.1 | Soft | County estimate |
| Lake Tapps | 95.3 | 5.6 | Moderately hard | Utility-reported |
| Clarkston | 96.0 | 5.6 | Moderately hard | County estimate |
| Walla Walla | 38.8 | 2.3 | Soft | County estimate |
| Ahtanum | 56.7 | 3.3 | Soft | Computed from Ca+Mg |
| Summitview | 56.7 | 3.3 | Soft | Computed from Ca+Mg |
| Country Homes | 124.0 | 7.3 | Hard | Utility-reported |
| Greenacres | 22.9 | 1.3 | Soft | County estimate |
| Manchester | 85.8 | 5.0 | Moderately hard | County estimate |
| Hobart | 62.7 | 3.7 | Moderately hard | County estimate |
| Centralia | 2.4 | 0.1 | Soft | County estimate |
| Cheney | 55.2 | 3.2 | Soft | Computed from Ca+Mg |
| Mead | 124.0 | 7.3 | Hard | Utility-reported |
| Green Bluff | 124.0 | 7.3 | Hard | Utility-reported |
| Mountlake Terrace | 14.3 | 0.8 | Soft | Utility-reported |
| Shelton | 38.6 | 2.3 | Soft | County estimate |
| Mercer Island | 39.4 | 2.3 | Soft | Utility-reported |
| Asotin | 96.0 | 5.6 | Moderately hard | County estimate |
| Sequim | 50.6 | 3.0 | Soft | County estimate |
| Poulsbo | 66.6 | 3.9 | Moderately hard | Utility-reported |
| Bainbridge Island | 70.1 | 4.1 | Moderately hard | Utility-reported |
| Cathcart | 43.3 | 2.5 | Soft | Utility-reported |
| Silver Firs | 43.3 | 2.5 | Soft | Utility-reported |
| Fobes Hill | 43.3 | 2.5 | Soft | Utility-reported |
| High Bridge | 43.3 | 2.5 | Soft | Utility-reported |
| Wollochet | 45.9 | 2.7 | Soft | Utility-reported |
| Lynden | 35.7 | 2.1 | Soft | County estimate |
| Ellensburg | 59.5 | 3.5 | Soft | Utility-reported |
| Gig Harbor | 45.9 | 2.7 | Soft | Utility-reported |
| East Renton Highlands | 30.0 | 1.8 | Soft | Utility-reported |
| Snoqualmie | 41.4 | 2.4 | Soft | Utility-reported |
| West Richland | 33.1 | 1.9 | Soft | Utility-reported |
| Aberdeen | 22.7 | 1.3 | Soft | County estimate |
| Port Townsend | 59.9 | 3.5 | Soft | Utility-reported |
| Enumclaw | 61.6 | 3.6 | Moderately hard | Utility-reported |
| Sunnyside | 74.8 | 4.4 | Moderately hard | County estimate |
| Esperance | 86.1 | 5.0 | Moderately hard | Utility-reported |
| Woodway | 86.1 | 5.0 | Moderately hard | Utility-reported |
| North Bend | 41.4 | 2.4 | Soft | Utility-reported |
| Snoqualime | 41.4 | 2.4 | Soft | Utility-reported |
| Yelm | 52.5 | 3.1 | Soft | County estimate |
| Sunnyslope | 80.0 | 4.7 | Moderately hard | Utility-reported |
| Hansville | 90.4 | 5.3 | Moderately hard | Utility-reported |
| Indianola | 90.4 | 5.3 | Moderately hard | Utility-reported |
| Kingston | 90.4 | 5.3 | Moderately hard | Utility-reported |
| Port Gamble Tribal Community | 90.4 | 5.3 | Moderately hard | Utility-reported |
| Sumner | 39.3 | 2.3 | Soft | County estimate |
| Kelso | 15.6 | 0.9 | Soft | County estimate |
| Newcastle | 27.4 | 1.6 | Soft | Utility-reported |
| Selah | 146.7 | 8.6 | Hard | Computed from Ca+Mg |
| Rosedale | 45.9 | 2.7 | Soft | Utility-reported |
| Stanwood | 28.6 | 1.7 | Soft | County estimate |
| Hoquiam | 22.7 | 1.3 | Soft | County estimate |
| Grandview | 208.2 | 12.2 | Very hard | Computed from Ca+Mg |
| Raymond | 15.6 | 0.9 | Soft | County estimate |
| Othello | 33.2 | 1.9 | Soft | Computed from Ca+Mg |
| Ocean Park | 15.6 | 0.9 | Soft | County estimate |
| Leavenworth | 14.7 | 0.9 | Soft | County estimate |
| Marrowstone | 157.0 | 9.2 | Hard | Utility-reported |
| Port Hadlock-Irondale | 157.0 | 9.2 | Hard | Utility-reported |
| Duvall | 21.0 | 1.2 | Soft | Utility-reported |
| Toppenish | 62.8 | 3.7 | Moderately hard | Computed from Ca+Mg |
| Chelan | 21.4 | 1.3 | Soft | Computed from Ca+Mg |
| Buckley | 39.3 | 2.3 | Soft | County estimate |
| Ocean Shores | 22.7 | 1.3 | Soft | County estimate |
| Terrace Heights | 88.1 | 5.2 | Moderately hard | Computed from Ca+Mg |
| Kalama | 15.6 | 0.9 | Soft | County estimate |
| Vashon | 62.7 | 3.7 | Moderately hard | County estimate |
| Manson | 14.7 | 0.9 | Soft | County estimate |
| Prosser | 74.8 | 4.4 | Moderately hard | County estimate |
| Benton City | 74.8 | 4.4 | Moderately hard | County estimate |
| Montesano | 22.7 | 1.3 | Soft | County estimate |
| Medical Lake | 22.9 | 1.3 | Soft | County estimate |
| Omak | 289.1 | 16.9 | Very hard | Computed from Ca+Mg |
| Cle Elum | 44.1 | 2.6 | Soft | County estimate |
| Mattawa | 168.0 | 9.8 | Hard | County estimate |
| Grayland | 15.6 | 0.9 | Soft | County estimate |
| Westport | 22.7 | 1.3 | Soft | County estimate |
| Belfair | 38.6 | 2.3 | Soft | County estimate |
| Eastsound | 163.0 | 9.5 | Hard | County estimate |
| Newport | 70.5 | 4.1 | Moderately hard | County estimate |
| Dallesport | 63.5 | 3.7 | Moderately hard | County estimate |
| Castle Rock | 15.6 | 0.9 | Soft | County estimate |
| Port Ludlow | 69.3 | 4.0 | Moderately hard | Utility-reported |
| Brewster | 117.0 | 6.8 | Moderately hard | County estimate |
| Suquamish | 85.8 | 5.0 | Moderately hard | County estimate |
| Coupeville | 289.0 | 16.9 | Very hard | County estimate |
| Ilwaco | 15.6 | 0.9 | Soft | County estimate |
| Tonasket | 235.7 | 13.8 | Very hard | Computed from Ca+Mg |
| Granger | 166.0 | 9.7 | Hard | County estimate |
| White Salmon | 63.5 | 3.7 | Moderately hard | County estimate |
| Hoodsport | 38.6 | 2.3 | Soft | County estimate |
| Napavine | 2.4 | 0.1 | Soft | County estimate |
| Fox Island | 39.3 | 2.3 | Soft | County estimate |
| Rochester | 52.5 | 3.1 | Soft | County estimate |
| Everson | 35.7 | 2.1 | Soft | County estimate |
| Nooksack | 35.7 | 2.1 | Soft | County estimate |
| Eatonville | 39.3 | 2.3 | Soft | County estimate |
| Colfax | 114.0 | 6.7 | Moderately hard | County estimate |
| Monroe | 28.6 | 1.7 | Soft | County estimate |
| Tenino | 52.5 | 3.1 | Soft | County estimate |
| Friday Harbor | 163.0 | 9.5 | Hard | County estimate |
| Zillah | 166.0 | 9.7 | Hard | County estimate |
| Naches | 166.0 | 9.7 | Hard | County estimate |
| Algona | 57.2 | 3.4 | Soft | Utility-reported |
| Royal City | 168.0 | 9.8 | Hard | County estimate |
| Dayton | 92.4 | 5.4 | Moderately hard | Computed from Ca+Mg |
| Oroville | 117.0 | 6.8 | Moderately hard | County estimate |
| Fall City | 62.7 | 3.7 | Moderately hard | County estimate |
| Okanogan | 117.0 | 6.8 | Moderately hard | County estimate |
| South Bend | 15.6 | 0.9 | Soft | County estimate |
| Winlock | 2.4 | 0.1 | Soft | County estimate |
| Rainier | 52.5 | 3.1 | Soft | County estimate |
| Mccleary | 22.7 | 1.3 | Soft | County estimate |
| Kettle Falls | 110.0 | 6.4 | Moderately hard | County estimate |
| Chewelah | 74.4 | 4.3 | Moderately hard | County estimate |
| Rock Island | 71.3 | 4.2 | Moderately hard | County estimate |
| Carnation | 62.7 | 3.7 | Moderately hard | County estimate |
| Mabton | 166.0 | 9.7 | Hard | County estimate |
| Stevenson | 37.5 | 2.2 | Soft | Computed from Ca+Mg |
| Kittitas | 44.1 | 2.6 | Soft | County estimate |
| Morton | 2.4 | 0.1 | Soft | County estimate |
| Darrington | 28.6 | 1.7 | Soft | County estimate |
| Allyn | 38.6 | 2.3 | Soft | County estimate |
| Roslyn | 44.1 | 2.6 | Soft | County estimate |
| Electric City | 168.0 | 9.8 | Hard | County estimate |
| Toledo | 2.4 | 0.1 | Soft | County estimate |
| Onalaska | 2.4 | 0.1 | Soft | County estimate |
| Clinton | 289.0 | 16.9 | Very hard | County estimate |
| Cosmopolis | 22.7 | 1.3 | Soft | County estimate |
| Waitsburg | 38.8 | 2.3 | Soft | County estimate |
| Newman Lake | 22.9 | 1.3 | Soft | County estimate |
| Bingen | 61.6 | 3.6 | Moderately hard | County estimate |
| Cashmere | 176.4 | 10.3 | Hard | Computed from Ca+Mg |
| Sumas | 35.7 | 2.1 | Soft | County estimate |
| Entiat | 14.7 | 0.9 | Soft | County estimate |
| Ritzville | 251.0 | 14.7 | Very hard | County estimate |
| Davenport | 149.0 | 8.7 | Hard | County estimate |
| Republic | 110.0 | 6.4 | Moderately hard | County estimate |
| Cathlamet | 56.6 | 3.3 | Soft | County estimate |
| Taholah | 22.7 | 1.3 | Soft | County estimate |
| La Conner | 9.0 | 0.5 | Soft | County estimate |
| Mossyrock | 2.4 | 0.1 | Soft | County estimate |
| Bow | 9.0 | 0.5 | Soft | County estimate |
| Pomeroy | 114.5 | 6.7 | Moderately hard | County estimate |
| Point Roberts | 35.7 | 2.1 | Soft | County estimate |
| Grand Coulee | 71.3 | 4.2 | Moderately hard | County estimate |
| Langley | 289.0 | 16.9 | Very hard | County estimate |
| Anderson Island | 39.3 | 2.3 | Soft | County estimate |
| Coulee Dam | 117.0 | 6.8 | Moderately hard | County estimate |
| Pacific Beach | 22.7 | 1.3 | Soft | County estimate |
| Oakville | 22.7 | 1.3 | Soft | County estimate |
| Harrah | 166.0 | 9.7 | Hard | County estimate |
| Neah Bay | 50.6 | 3.0 | Soft | County estimate |
| Palouse | 114.0 | 6.7 | Moderately hard | County estimate |
| Pateros | 281.3 | 16.4 | Very hard | Computed from Ca+Mg |
| Waterville | 71.3 | 4.2 | Moderately hard | County estimate |
| Ephrata | 230.3 | 13.5 | Very hard | Computed from Ca+Mg |
| Camano Island | 289.0 | 16.9 | Very hard | County estimate |
| Ashford | 39.3 | 2.3 | Soft | County estimate |
| Wilkeson | 39.3 | 2.3 | Soft | County estimate |
| North Bonneville | 61.6 | 3.6 | Moderately hard | County estimate |
| Tekoa | 114.0 | 6.7 | Moderately hard | County estimate |
| George | 149.6 | 8.8 | Hard | Computed from Ca+Mg |
| Twisp | 117.0 | 6.8 | Moderately hard | County estimate |
| Chimacum | 25.4 | 1.5 | Soft | County estimate |
| Union | 38.6 | 2.3 | Soft | County estimate |
| Quinault | 22.7 | 1.3 | Soft | County estimate |
| Vader | 2.4 | 0.1 | Soft | County estimate |
| Buena | 166.0 | 9.7 | Hard | County estimate |
| St. John | 114.0 | 6.7 | Moderately hard | County estimate |
| Tokeland | 15.6 | 0.9 | Soft | County estimate |
| Yacolt | 61.2 | 3.6 | Moderately hard | Computed from Ca+Mg |
| Cusick | 70.5 | 4.1 | Moderately hard | County estimate |
| Malott | 117.0 | 6.8 | Moderately hard | County estimate |
| Malaga | 14.7 | 0.9 | Soft | County estimate |
| Colton | 114.0 | 6.7 | Moderately hard | County estimate |
| Albion | 114.0 | 6.7 | Moderately hard | County estimate |
| Bucoda | 52.5 | 3.1 | Soft | County estimate |
| South Cle Elum | 19.5 | 1.1 | Soft | Computed from Ca+Mg |
| Marshall | 22.9 | 1.3 | Soft | County estimate |
| Prescott | 38.8 | 2.3 | Soft | County estimate |
| Oakesdale | 114.0 | 6.7 | Moderately hard | County estimate |
| Carson | 61.6 | 3.6 | Moderately hard | County estimate |
| Riverside | 117.0 | 6.8 | Moderately hard | County estimate |
| Ronald | 44.1 | 2.6 | Soft | County estimate |
| Moses Lake | 168.0 | 9.8 | Hard | County estimate |
| Uniontown | 114.0 | 6.7 | Moderately hard | County estimate |
| Ferndale | 35.7 | 2.1 | Soft | County estimate |
| Bridgeport | 206.7 | 12.1 | Very hard | Computed from Ca+Mg |
| Usk | 70.5 | 4.1 | Moderately hard | County estimate |
| Quincy | 168.0 | 9.8 | Hard | County estimate |
| Wapato | 166.0 | 9.7 | Hard | County estimate |
| Peshastin | 14.7 | 0.9 | Soft | County estimate |
| Orondo | 71.3 | 4.2 | Moderately hard | County estimate |
| Nespelem | 117.0 | 6.8 | Moderately hard | County estimate |
| Grapeview | 38.6 | 2.3 | Soft | County estimate |
| Port Angeles | 50.6 | 3.0 | Soft | County estimate |
| Freeland | 289.0 | 16.9 | Very hard | County estimate |
| Lind | 251.0 | 14.7 | Very hard | County estimate |
| Lopez Island | 163.0 | 9.5 | Hard | County estimate |
| Maple Falls | 35.7 | 2.1 | Soft | County estimate |
| Mesa | 268.5 | 15.7 | Very hard | County estimate |
| Packwood | 2.4 | 0.1 | Soft | County estimate |
| Trout Lake | 63.5 | 3.7 | Moderately hard | County estimate |
| Waverly | 22.9 | 1.3 | Soft | County estimate |
| Winthrop | 117.0 | 6.8 | Moderately hard | County estimate |
Above 120 mg/L (7 gpg), scale is usually worth treating — see our water softener guide, or size a system with the hardness calculator & converter.
The Geology Behind Washington's Water Hardness
Washington sits in the Pacific maritime volcanic terrain region.
The Pacific Northwest, Alaska, and Hawaii share young volcanic bedrock - basalt and other igneous rock with little carbonate to dissolve - and most supplies come from heavy rainfall, snowmelt, or fast-recharging volcanic aquifers. Water simply does not stay in contact with soluble carbonate long enough to harden. That is why the USGS maps these states among the softest in the nation.
Washington Water Hardness FAQ
Does Washington have hard water?
On the whole, no — Washington's statewide median sits below the hard threshold, though some cities run harder. The median is 41.4 mg/L (2.4 gpg) — soft on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 21 of Washington's 227 measured cities fall in the hard or very hard bands (9%), so check your own city rather than the state average.
How hard is tap water in Washington?
Across the 227 Washington cities with measured values in our index, the median hardness is 41.4 mg/L (2.4 gpg) — soft on the USGS scale. Individual cities range from 12.6 to 289.1 mg/L, so check your own city rather than assuming the state number.
Which city in Washington has the hardest water?
Omak has the hardest measured tap water in our Washington index at 289.1 mg/L (16.9 gpg) — very hard on the USGS scale. Rankings use measured utility values only; labeled county estimates and values under active dispute are excluded.
Do I need a water softener in Washington?
21 of Washington's 227 measured cities (9%) fall in the hard or very hard bands — above 120 mg/L (7 gpg), the level where most water treatment professionals suggest considering an ion-exchange softener. Hardness varies utility to utility, so look up your own city's value before sizing equipment.
How do I find my city's exact water hardness?
Enter your ZIP code in our free lookup at tapwaterdata.com/zip to see the value we hold for your Washington city from utility-reported water quality data, check your water utility's annual Consumer Confidence Report (CCR), or use a home test-strip kit.
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