How hard is the water in Putnam County, TN?

8.8 grains per gallon

A softener is worth it here.

The median hardness measured in Putnam County, TN is 150 mg/L as calcium carbonate, which is 8.8 gpg. That is hard on the USGS scale. It comes from 329 samples at 19 sites between 1999 and 2020, drawn from every sampling site in the county, wells and surface water together.

How much it varies here

Half the sites came in between 7.7 and 9.3 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: high (how it is measured).

What to do next

At 8.8 gpg a softener is worth getting, mainly to protect the water heater and cut soap use. Get at least two quotes, ask each installer what grain capacity they are fitting, and check it against the sizing table below.

More on sizing a softener for your household.

From 2.5 to 11.0 gpg

The softest single sample on record in Putnam County was 43 mg/L and the hardest 188 mg/L, a 4-fold gap. The top quarter of sites read above 9.3 gpg and the bottom quarter below 7.7 gpg. So even here some sites draw water soft enough to need nothing at all.

What a softener would cost to run

For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 191 lb of salt a year (5 bags of 40 lb, about $34), 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 $134 a year.

Sizing at 8.8 gpg

Putnam County against the rest of Tennessee

Among the 95 Tennessee counties with data, Putnam County is number 32 of 95 counting from the hardest. Across the whole country it is harder than 46% of counties.

Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Putnam County: Blount County (8.7), Cannon County (8.7), Bradley County (8.8).