How hard is the water in Washington County, TN?
14.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Washington County, TN is 248 mg/L as calcium carbonate, which is 14.5 gpg. That is very hard on the USGS scale. It comes from 707 samples at 64 sites between 1995 and 2019, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 11.9 and 15.5 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 14.5 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 18.5 gpg
The softest single sample on record in Washington County was 0.2 mg/L and the hardest 316 mg/L, a 1,580-fold gap. The top quarter of sites read above 15.5 gpg and the bottom quarter below 11.9 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 13.8 gpg, rivers and lakes 14.5 gpg
4 groundwater samples from 4 wells put the median at 235.5 mg/L. 703 surface samples from 60 sites put it at 247.5 mg/L. In Washington County the rivers and lakes come out 0.7 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. 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 316 lb of salt a year (8 bags of 40 lb, about $57), 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 $157 a year.
Sizing at 14.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 870 | 24,000 | 106 lb |
| 2 | 1,740 | 24,000 | 212 lb |
| 4 | 3,480 | 32,000 | 423 lb |
| 6 | 5,220 | 40,000 | 635 lb |
Washington County against the rest of Tennessee
Among the 95 Tennessee counties with data, Washington County is number 9 of 95 counting from the hardest. Across the whole country it is harder than 68% of counties.
Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Washington County: Sullivan County (14.5), Hamblen County (14.7), Greene County (14.3).