How hard is the water in Union Parish, LA?
0.4 grains per gallon
You do not need a softener here.
The median hardness measured in Union Parish, LA is 7 mg/L as calcium carbonate, which is 0.4 gpg. That is soft on the USGS scale. It comes from 75 samples at 11 sites between 1999 and 2023, 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 0.2 and 0.7 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 0.4 gpg the most a softener would fix is the odd water spot. If a salesperson in Union Parish 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 0.1 to 1.8 gpg
The softest single sample on record in Union Parish was 1.4 mg/L and the hardest 30.7 mg/L, a 22-fold gap. The top quarter of sites read above 0.7 gpg and the bottom quarter below 0.2 gpg.
Wells 0.4 gpg, rivers and lakes 1.4 gpg
75 groundwater samples from 11 wells put the median at 6.7 mg/L. 213 surface samples from 5 sites put it at 24.4 mg/L. In Union Parish the rivers and lakes come out 1.0 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.
Union Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, Union Parish is number 57 of 64 counting from the hardest. Across the whole country it is harder than 2% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to Union Parish: St. Helena Parish (0.3), East Baton Rouge Parish (0.5), East Feliciana Parish (0.4).