How hard is the water in De Soto Parish, LA?
1.1 grains per gallon
You do not need a softener here.
The median hardness measured in De Soto Parish, LA is 20 mg/L as calcium carbonate, which is 1.1 gpg. That is soft on the USGS scale. It comes from 42 samples at 32 sites between 1990 and 2024, 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 0.4 and 3.6 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
You can skip the softener. At 1.1 gpg the most a softener would fix is the odd water spot. If a salesperson in De Soto Parish says otherwise, ask to see their reading in grains per gallon and compare it with this one. Because De Soto Parish 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 0.1 to 22.4 gpg
The softest single sample on record in De Soto Parish was 1.1 mg/L and the hardest 383 mg/L, a 348-fold gap. The top quarter of sites read above 3.6 gpg and the bottom quarter below 0.4 gpg. So even in a soft county, a handful of wells here produce water hard enough to scale a heater.
Wells 1.1 gpg, rivers and lakes 3.2 gpg
42 groundwater samples from 32 wells put the median at 19.5 mg/L. 146 surface samples from 4 sites put it at 55.5 mg/L. In De Soto Parish the rivers and lakes come out 2.1 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.
De Soto Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, De Soto Parish is number 46 of 64 counting from the hardest. Across the whole country it is harder than 8% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to De Soto Parish: Beauregard Parish (0.9), West Feliciana Parish (0.8), LaSalle Parish (1.5).