How hard is the water in Cumberland County, ME?
2.4 grains per gallon
You do not need a softener here.
The median hardness measured in Cumberland County, ME is 42 mg/L as calcium carbonate, which is 2.4 gpg. That is soft on the USGS scale. It comes from 136 samples at 59 sites between 1990 and 2019, 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 1.4 and 3.4 gpg. The whole middle of that range gives the same answer, so a test of your own tap is unlikely to change it. Confidence in the county figure: high (how it is measured).
What to do next
You can skip the softener. At 2.4 gpg the most a softener would fix is the odd water spot. If a salesperson in Cumberland County says otherwise, ask to see their reading in grains per gallon and compare it with this one.
More on when a softener is not worth it.
From 0.7 to 15.2 gpg
The softest single sample on record in Cumberland County was 11.5 mg/L and the hardest 260 mg/L, a 23-fold gap. The top quarter of sites read above 3.4 gpg and the bottom quarter below 1.4 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.
Wells 2.4 gpg, rivers and lakes 0.9 gpg
136 groundwater samples from 59 wells put the median at 41.5 mg/L. 94 surface samples from 9 sites put it at 15.7 mg/L. In Cumberland County the wells come out 1.5 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.
Cumberland County against the rest of Maine
Among the 16 Maine counties with data, Cumberland County is number 11 of 16 counting from the hardest. Across the whole country it is harder than 19% of counties.
Softest in Maine: Lincoln County at 0.7 gpg. Hardest: Penobscot County at 6.9 gpg. Closest to Cumberland County: Hancock County (2.1), Oxford County (2.8), Piscataquis County (1.8).