How hard is the water in Pierce County, WA?
3.2 grains per gallon
You do not need a softener here.
The median hardness measured in Pierce County, WA is 55 mg/L as calcium carbonate, which is 3.2 gpg. That is soft on the USGS scale. It comes from 254 samples at 169 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 2.8 and 4.6 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 Pierce County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because Pierce 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 0.4 to 17.3 gpg
The softest single sample on record in Pierce County was 7.4 mg/L and the hardest 296.5 mg/L, a 40-fold gap. The top quarter of sites read above 4.6 gpg and the bottom quarter below 2.8 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 2.2 gpg
254 groundwater samples from 169 wells put the median at 55.1 mg/L. 171 surface samples from 13 sites put it at 36.9 mg/L. In Pierce County the wells come out 1.0 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.
Pierce County against the rest of Washington
Among the 38 Washington counties with data, Pierce County is number 28 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 Pierce County: Spokane County (3.2), Benton County (3.3), Skamania County (3.3).