How hard is the water in Kittitas County, WA?
2.6 grains per gallon
You do not need a softener here.
The median hardness measured in Kittitas County, WA is 44 mg/L as calcium carbonate, which is 2.6 gpg. That is soft on the USGS scale. It comes from 21 samples at 21 sites between 1990 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 6.5 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: medium (how it is measured).
What to do next
You can skip the softener. At 2.6 gpg the most a softener would fix is the odd water spot. If a salesperson in Kittitas County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because Kittitas 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 0.2 to 16.3 gpg
The softest single sample on record in Kittitas County was 3 mg/L and the hardest 279 mg/L, a 93-fold gap. The top quarter of sites read above 6.5 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 2.6 gpg, rivers and lakes 3.8 gpg
21 groundwater samples from 21 wells put the median at 44.1 mg/L. 29 surface samples from 11 sites put it at 65.5 mg/L. In Kittitas County the rivers and lakes come out 1.2 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. The two sources are close, so the county figure should hold whichever one your tap is on.
Kittitas County against the rest of Washington
Among the 38 Washington counties with data, Kittitas County is number 31 of 38 counting from the hardest. Across the whole country it is harder than 20% of counties.
Softest in Washington: Chelan County at 0.6 gpg. Hardest: Island County at 20.7 gpg. Closest to Kittitas County: Clallam County (2.5), Mason County (2.6), Pacific County (2.3).