How hard is the water in Jefferson County, TN?
16.8 grains per gallon
A softener will pay its way here.
The median hardness measured in Jefferson County, TN is 287 mg/L as calcium carbonate, which is 16.8 gpg. That is very hard on the USGS scale. It comes from 8 samples at 7 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 15.6 and 17.3 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: medium (how it is measured).
What to do next
At 16.8 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.
More on sizing a softener for your household.
From 12.3 to 19.5 gpg
The softest single sample on record in Jefferson County was 211 mg/L and the hardest 334 mg/L, a 2-fold gap. The top quarter of sites read above 17.3 gpg and the bottom quarter below 15.6 gpg.
Wells 16.8 gpg, rivers and lakes 14.6 gpg
8 groundwater samples from 7 wells put the median at 287 mg/L. 23 surface samples from 3 sites put it at 250 mg/L. In Jefferson County the wells come out 2.2 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 366 lb of salt a year (10 bags of 40 lb, about $66), 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 $166 a year.
Sizing at 16.8 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 1,008 | 24,000 | 123 lb |
| 2 | 2,016 | 24,000 | 245 lb |
| 4 | 4,032 | 32,000 | 491 lb |
| 6 | 6,048 | 48,000 | 736 lb |
Jefferson County against the rest of Tennessee
Among the 95 Tennessee counties with data, Jefferson County is number 5 of 95 counting from the hardest. Across the whole country it is harder than 75% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Jefferson County: Maury County (17.2), Marshall County (17.7), Hawkins County (15.2).