How hard is the water in Union County, TN?
11.7 grains per gallon
A softener will pay its way here.
The median hardness measured in Union County, TN is 200 mg/L as calcium carbonate, which is 11.7 gpg. That is very hard on the USGS scale. It comes from 8 samples at 6 sites between 1990 and 2022, 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 10 and 13.1 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: medium (how it is measured).
What to do next
At 11.7 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water. Because Union County straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on sizing a softener for your household.
From 9.4 to 19.2 gpg
The softest single sample on record in Union County was 161 mg/L and the hardest 329 mg/L, a 2-fold gap. The top quarter of sites read above 13.1 gpg and the bottom quarter below 10 gpg.
Wells 11.7 gpg, rivers and lakes 10.7 gpg
8 groundwater samples from 6 wells put the median at 200 mg/L. 59 surface samples from 8 sites put it at 182.8 mg/L. In Union County the wells come out 1.0 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. 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 255 lb of salt a year (7 bags of 40 lb, about $46), 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 $146 a year.
Sizing at 11.7 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 702 | 24,000 | 85 lb |
| 2 | 1,404 | 24,000 | 171 lb |
| 4 | 2,808 | 24,000 | 342 lb |
| 6 | 4,212 | 32,000 | 512 lb |
Union County against the rest of Tennessee
Among the 95 Tennessee counties with data, Union County is number 17 of 95 counting from the hardest. Across the whole country it is harder than 57% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Union County: Trousdale County (11.6), Rutherford County (11.8), Knox County (12).