How hard is the water in El Dorado County, CA?
2.6 grains per gallon
You do not need a softener here.
The median hardness measured in El Dorado County, CA is 44 mg/L as calcium carbonate, which is 2.6 gpg. That is soft on the USGS scale. It comes from 305 samples at 105 sites between 1990 and 2022, 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 1.6 and 5.6 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 2.6 gpg the most a softener would fix is the odd water spot. If a salesperson in El Dorado County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because El Dorado 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 32.9 gpg
The softest single sample on record in El Dorado County was 4 mg/L and the hardest 564 mg/L, a 141-fold gap. The top quarter of sites read above 5.6 gpg and the bottom quarter below 1.6 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 0.7 gpg
305 groundwater samples from 105 wells put the median at 44 mg/L. 73 surface samples from 13 sites put it at 12.6 mg/L. In El Dorado County the wells come out 1.9 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.
El Dorado County against the rest of California
Among the 58 California counties with data, El Dorado County is number 57 of 58 counting from the hardest. Across the whole country it is harder than 20% of counties.
Softest in California: Sierra County at 1.7 gpg. Hardest: Calaveras County at 98.3 gpg. Closest to El Dorado County: Mariposa County (2.7), Tuolumne County (2.8), Sierra County (1.7).