How hard is the water in Shelby County, TN?
4.8 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Shelby County, TN is 83 mg/L as calcium carbonate, which is 4.8 gpg. That is moderately hard on the USGS scale. It comes from 657 samples at 186 sites between 1990 and 2033, 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 2.2 and 11 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 4.8 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 Shelby 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 0.3 to 40.7 gpg
The softest single sample on record in Shelby County was 5.8 mg/L and the hardest 696 mg/L, a 120-fold gap. The top quarter of sites read above 11 gpg and the bottom quarter below 2.2 gpg.
Wells 4.8 gpg, rivers and lakes 3.1 gpg
657 groundwater samples from 186 wells put the median at 82.6 mg/L. 3,459 surface samples from 188 sites put it at 52.3 mg/L. In Shelby County the wells come out 1.7 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. 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 105 lb of salt a year (3 bags of 40 lb, about $19), 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 $119 a year.
Sizing at 4.8 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 288 | 24,000 | 35 lb |
| 2 | 576 | 24,000 | 70 lb |
| 4 | 1,152 | 24,000 | 140 lb |
| 6 | 1,728 | 24,000 | 210 lb |
Shelby County against the rest of Tennessee
Among the 95 Tennessee counties with data, Shelby County is number 59 of 95 counting from the hardest. Across the whole country it is harder than 30% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Shelby County: Smith County (5), Rhea County (5.1), Bledsoe County (4.2).