How hard is the water in Sussex County, DE?

2 grains per gallon

You do not need a softener here.

The median hardness measured in Sussex County, DE is 35 mg/L as calcium carbonate, which is 2 gpg. That is soft on the USGS scale. It comes from 529 samples at 302 sites between 1990 and 2026, 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 0.9 and 3.7 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 gpg the most a softener would fix is the odd water spot. If a salesperson in Sussex County says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because Sussex 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 12.9 gpg

The softest single sample on record in Sussex County was 0.5 mg/L and the hardest 221 mg/L, a 442-fold gap. The top quarter of sites read above 3.7 gpg and the bottom quarter below 0.9 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.

Wells 2 gpg, rivers and lakes 2.1 gpg

529 groundwater samples from 302 wells put the median at 34.5 mg/L. 14,183 surface samples from 277 sites put it at 36.8 mg/L. In Sussex County the rivers and lakes come out 0.1 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.

Sussex County against the rest of Delaware

Among the 3 Delaware counties with data, Sussex County is the softest. Across the whole country it is harder than 16% of counties.

Hardest: New Castle County at 5.8 gpg. Closest to Sussex County: Kent County (4.2), New Castle County (5.8).