How hard is the water in Kent County, DE?
4.2 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Kent County, DE is 73 mg/L as calcium carbonate, which is 4.2 gpg. That is moderately hard on the USGS scale. It comes from 94 samples at 47 sites between 1990 and 2025, 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 2.7 and 7.1 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
At 4.2 gpg this is your call. Look for white film on glasses and crust on the shower head: if you see little of either, you can live without one. If you do want one, a 24,000-grain unit is enough, so ask for that size rather than a bigger one. Because Kent 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 0.7 to 11.9 gpg
The softest single sample on record in Kent County was 11.9 mg/L and the hardest 203 mg/L, a 17-fold gap. The top quarter of sites read above 7.1 gpg and the bottom quarter below 2.7 gpg.
Wells 4.2 gpg, rivers and lakes 3.4 gpg
94 groundwater samples from 47 wells put the median at 72.5 mg/L. 10,593 surface samples from 203 sites put it at 59 mg/L. In Kent County the wells come out 0.8 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.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 92 lb of salt a year (3 bags of 40 lb, about $17), and roughly 2,346 gallons of regeneration water. Installed, most units run $1,000 to $4,500; spread over 15 years with salt, that is about $117 a year.
Sizing at 4.2 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 252 | 24,000 | 31 lb |
| 2 | 504 | 24,000 | 61 lb |
| 4 | 1,008 | 24,000 | 123 lb |
| 6 | 1,512 | 24,000 | 184 lb |
Kent County against the rest of Delaware
Among the 3 Delaware counties with data, Kent County is number 2 of 3 counting from the hardest. Across the whole country it is harder than 27% of counties.
Softest in Delaware: Sussex County at 2 gpg. Hardest: New Castle County at 5.8 gpg. Closest to Kent County: New Castle County (5.8), Sussex County (2).