How hard is the water in Anne Arundel County, MD?
2.1 grains per gallon
You do not need a softener here.
The median hardness measured in Anne Arundel County, MD is 36 mg/L as calcium carbonate, which is 2.1 gpg. That is soft on the USGS scale. It comes from 151 samples at 131 sites between 1990 and 2023, 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 0.8 and 7.4 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 2.1 gpg the most a softener would fix is the odd water spot. If a salesperson in Anne Arundel County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because Anne Arundel 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 0.0 to 204.5 gpg
The softest single sample on record in Anne Arundel County was 0.4 mg/L and the hardest 3,500 mg/L, an 8,750-fold gap. The top quarter of sites read above 7.4 gpg and the bottom quarter below 0.8 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.
Wells 2.1 gpg, rivers and lakes 3.7 gpg
151 groundwater samples from 131 wells put the median at 35.7 mg/L. 140 surface samples from 11 sites put it at 62.9 mg/L. In Anne Arundel County the rivers and lakes come out 1.6 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.
Anne Arundel County against the rest of Maryland
Among the 24 Maryland counties with data, Anne Arundel County is number 21 of 24 counting from the hardest. Across the whole country it is harder than 17% of counties.
Softest in Maryland: Charles County at 0.3 gpg. Hardest: Washington County at 18.5 gpg. Closest to Anne Arundel County: Caroline County (2.3), Howard County (2.5), Wicomico County (1.7).