How hard is the water in Spokane County, WA?

3.2 grains per gallon

You do not need a softener here.

The median hardness measured in Spokane County, WA is 55 mg/L as calcium carbonate, which is 3.2 gpg. That is soft on the USGS scale. It comes from 171 samples at 38 sites between 1994 and 2016, drawn from groundwater wells, which is what most taps and private wells in the county draw on.

How much it varies here

Half the sites came in between 1.3 and 8.7 gpg. That spread crosses a decision line, so some homes here land on a different answer. A $10 test strip on your own tap settles it. Confidence in the county figure: high (how it is measured).

What to do next

You can skip the softener. At 3.2 gpg the most a softener would fix is the odd water spot. If a salesperson in Spokane County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because Spokane County straddles a decision line, check your own tap with a $10 test strip before you spend anything.

More on when a softener is not worth it.

From 1.2 to 13.3 gpg

The softest single sample on record in Spokane County was 19.8 mg/L and the hardest 228 mg/L, a 12-fold gap. The top quarter of sites read above 8.7 gpg and the bottom quarter below 1.3 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.

Wells 3.2 gpg, rivers and lakes 2.1 gpg

171 groundwater samples from 38 wells put the median at 55.4 mg/L. 151 surface samples from 16 sites put it at 36.3 mg/L. In Spokane County the wells come out 1.1 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. The two sources are close, so the county figure should hold whichever one your tap is on.

Spokane County against the rest of Washington

Among the 38 Washington counties with data, Spokane County is number 27 of 38 counting from the hardest. Across the whole country it is harder than 23% of counties.

Softest in Washington: Chelan County at 0.6 gpg. Hardest: Island County at 20.7 gpg. Closest to Spokane County: Pierce County (3.2), Benton County (3.3), Skamania County (3.3).