How hard is the water in Plymouth County, MA?

1.3 grains per gallon

You do not need a softener here.

The median hardness measured in Plymouth County, MA is 23 mg/L as calcium carbonate, which is 1.3 gpg. That is soft on the USGS scale. It comes from 243 samples at 79 sites between 1990 and 2021, 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 0.7 and 2.2 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 1.3 gpg the most a softener would fix is the odd water spot. If a salesperson in Plymouth 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 0.2 to 12.2 gpg

The softest single sample on record in Plymouth County was 3.5 mg/L and the hardest 209.5 mg/L, a 60-fold gap. The top quarter of sites read above 2.2 gpg and the bottom quarter below 0.7 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.

Wells 1.3 gpg, rivers and lakes 2.8 gpg

243 groundwater samples from 79 wells put the median at 22.9 mg/L. 90 surface samples from 9 sites put it at 47.1 mg/L. In Plymouth County the rivers and lakes come out 1.5 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.

Plymouth County against the rest of Massachusetts

Among the 12 Massachusetts counties with data, Plymouth County is number 11 of 12 counting from the hardest. Across the whole country it is harder than 10% of counties.

Softest in Massachusetts: Barnstable County at 1.3 gpg. Hardest: Berkshire County at 8.9 gpg. Closest to Plymouth County: Barnstable County (1.3), Franklin County (2.2), Norfolk County (2.4).