Water Hardness in Washington (WA)
Washington has an average water hardness of 25 ppm (1.5 grains per gallon), which is classified as Soft . Washington enjoys naturally soft water that requires no softening treatment. Residents benefit from easy soap lathering, spot-free dishes, and long-lasting plumbing and appliances. Water hardness varies between cities — from 10 ppm in Vancouver to 75 ppm in Spokane.
Water Hardness by City in Washington
The table below shows water hardness data for 8 cities in Washington, sorted from hardest to softest. Click any city name for detailed information including water source, treatment recommendations, and estimated hard water costs.
| City | Hardness (PPM) | Grains/Gallon | Level | Water Source | pH | TDS | Utility |
|---|---|---|---|---|---|---|---|
| Spokane | 75 ppm | 4.4 gpg | Slightly Hard | Ground | 7.3 | 115 | City of Spokane Water Department |
| Kennewick | 65 ppm | 3.8 gpg | Slightly Hard | Surface | 7.3 | 100 | City of Kennewick |
| Yakima | 55 ppm | 3.2 gpg | Soft | Mixed | 7.2 | 82 | City of Yakima Water Division |
| Bellingham | 28 ppm | 1.6 gpg | Soft | Surface | 7 | 44 | City of Bellingham Public Works |
| Seattle | 22 ppm | 1.3 gpg | Soft | Surface | 7.1 | 35 | Seattle Public Utilities |
| Olympia | 22 ppm | 1.3 gpg | Soft | Ground | 7 | 35 | City of Olympia Water Resources |
| Tacoma | 15 ppm | 0.9 gpg | Soft | Surface | 6.8 | 24 | Tacoma Public Utilities |
| Vancouver | 10 ppm | 0.6 gpg | Soft | Ground | 6.8 | 18 | City of Vancouver Water Utility |
Understanding Water Hardness in Washington
Water Sources in Washington
The majority of cities in Washington draw their water from surface sources such as rivers, lakes, and reservoirs. Surface water generally contains fewer dissolved minerals than groundwater, which helps explain the overall hardness profile of the state. Cities that rely on surface water tend to have softer water because the water has less contact time with mineral-bearing rock formations underground.
Hardness Variation Across Washington
Water hardness in Washington ranges from 10 ppm in Vancouver to 75 ppm in Spokane — a difference of 65 ppm. This variation means that treatment recommendations differ significantly between cities. Even the hardest water in Washington is moderate enough that a water softener is optional rather than essential, though homeowners who value spotless dishes and softer-feeling water may still find one worthwhile. Meanwhile, Vancouver enjoys naturally soft water that needs no treatment at all — an advantage that saves residents money on both equipment and ongoing maintenance.
How Washington Compares to Other States
Below is a comparison of Washington with five states that have similar average water hardness levels. Understanding how your state compares can help you gauge whether your water is typical for the region or unusually hard or soft.
| State | Avg Hardness | Level | Cities |
|---|---|---|---|
| Washington (WA) | 25 ppm | Soft | 8 |
| Massachusetts (MA) | 20 ppm | Soft | 8 |
| Oregon (OR) | 30 ppm | Soft | 8 |
| Rhode Island (RI) | 30 ppm | Soft | 8 |
| Vermont (VT) | 20 ppm | Soft | 8 |
| Connecticut (CT) | 35 ppm | Soft | 8 |
Find Your City's Water Hardness
Use our water hardness lookup tool to find your specific city in Washington, or browse all 50 states to compare water hardness across the country. If your water is hard, visit our treatment solutions guide to find the right softener or conditioner for your home.