How hard is the water in Madison County, TN?

2.3 grains per gallon

You do not need a softener here.

The median hardness measured in Madison County, TN is 40 mg/L as calcium carbonate, which is 2.3 gpg. That is soft on the USGS scale. It comes from 55 samples at 49 sites between 1990 and 2022, 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 1.3 and 3.1 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

You can skip the softener. At 2.3 gpg the most a softener would fix is the odd water spot. If a salesperson in Madison County says otherwise, ask to see their reading in grains per gallon and compare it with this one.

More on when a softener is not worth it.

From 0.3 to 11.2 gpg

The softest single sample on record in Madison County was 4.7 mg/L and the hardest 191 mg/L, a 41-fold gap. The top quarter of sites read above 3.1 gpg and the bottom quarter below 1.3 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.

Wells 2.3 gpg, rivers and lakes 1.1 gpg

55 groundwater samples from 49 wells put the median at 40 mg/L. 379 surface samples from 47 sites put it at 18 mg/L. In Madison County the wells come out 1.2 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.

Madison County against the rest of Tennessee

Among the 95 Tennessee counties with data, Madison County is number 76 of 95 counting from the hardest. Across the whole country it is harder than 18% of counties.

Softest in Tennessee: Fayette County at 0.5 gpg. Hardest: Fentress County at 42.9 gpg. Closest to Madison County: Johnson County (2.3), Haywood County (2.3), Franklin County (2.4).