How hard is the water in DeKalb County, TN?
5.6 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in DeKalb County, TN is 96 mg/L as calcium carbonate, which is 5.6 gpg. That is moderately hard on the USGS scale. It comes from 1,963 samples at 49 sites between 1990 and 2020, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 4.5 and 11.6 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 5.6 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 DeKalb 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 3.9 to 29.4 gpg
The softest single sample on record in DeKalb County was 67.4 mg/L and the hardest 503 mg/L, a 7-fold gap. The top quarter of sites read above 11.6 gpg and the bottom quarter below 4.5 gpg.
Wells 13.4 gpg, rivers and lakes 5.4 gpg
4 groundwater samples from 3 wells put the median at 230 mg/L. 1,959 surface samples from 46 sites put it at 92.4 mg/L. In DeKalb County the wells come out 8.0 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 122 lb of salt a year (4 bags of 40 lb, about $22), 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 $122 a year.
Sizing at 5.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 336 | 24,000 | 41 lb |
| 2 | 672 | 24,000 | 82 lb |
| 4 | 1,344 | 24,000 | 164 lb |
| 6 | 2,016 | 24,000 | 245 lb |
DeKalb County against the rest of Tennessee
Among the 95 Tennessee counties with data, DeKalb County is number 56 of 95 counting from the hardest. Across the whole country it is harder than 33% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to DeKalb County: Clay County (5.8), Obion County (5.8), White County (5.8).