How hard is the water in Rutherford County, TN?
11.8 grains per gallon
A softener will pay its way here.
The median hardness measured in Rutherford County, TN is 203 mg/L as calcium carbonate, which is 11.8 gpg. That is very hard on the USGS scale. It comes from 1,239 samples at 98 sites between 1990 and 5005, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 10.9 and 14.1 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 11.8 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 7.0 to 18.3 gpg
The softest single sample on record in Rutherford County was 120 mg/L and the hardest 314 mg/L, a 3-fold gap. The top quarter of sites read above 14.1 gpg and the bottom quarter below 10.9 gpg.
Wells 16.4 gpg, rivers and lakes 11.7 gpg
1 groundwater samples from 1 wells put the median at 280 mg/L. 1,238 surface samples from 97 sites put it at 201 mg/L. In Rutherford County the wells come out 4.7 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 258 lb of salt a year (7 bags of 40 lb, about $47), 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 $147 a year.
Sizing at 11.8 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 708 | 24,000 | 86 lb |
| 2 | 1,416 | 24,000 | 172 lb |
| 4 | 2,832 | 24,000 | 345 lb |
| 6 | 4,248 | 32,000 | 517 lb |
Rutherford County against the rest of Tennessee
Among the 95 Tennessee counties with data, Rutherford County is number 16 of 95 counting from the hardest. Across the whole country it is harder than 58% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Rutherford County: Knox County (12), Wilson County (11.9), Union County (11.7).