How hard is the water in Grainger County, TN?
13.3 grains per gallon
A softener will pay its way here.
The median hardness measured in Grainger County, TN is 227 mg/L as calcium carbonate, which is 13.3 gpg. That is very hard on the USGS scale. It comes from 39 samples at 39 sites between 1991 and 2015, 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 11.1 and 16.9 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: high (how it is measured).
What to do next
At 13.3 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 0.0 to 26.7 gpg
The softest single sample on record in Grainger County was 0.3 mg/L and the hardest 457 mg/L, a 1,523-fold gap. The top quarter of sites read above 16.9 gpg and the bottom quarter below 11.1 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 13.3 gpg, rivers and lakes 10.5 gpg
39 groundwater samples from 39 wells put the median at 227 mg/L. 24 surface samples from 3 sites put it at 180 mg/L. In Grainger County the wells come out 2.8 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 290 lb of salt a year (8 bags of 40 lb, about $52), 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 $152 a year.
Sizing at 13.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 798 | 24,000 | 97 lb |
| 2 | 1,596 | 24,000 | 194 lb |
| 4 | 3,192 | 24,000 | 388 lb |
| 6 | 4,788 | 40,000 | 583 lb |
Grainger County against the rest of Tennessee
Among the 95 Tennessee counties with data, Grainger County is number 12 of 95 counting from the hardest. Across the whole country it is harder than 63% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Grainger County: Hancock County (13.7), Greene County (14.3), Davidson County (12.2).