How hard is the water in Jefferson Davis Parish, LA?
9.3 grains per gallon
A softener is worth it here.
The median hardness measured in Jefferson Davis Parish, LA is 159 mg/L as calcium carbonate, which is 9.3 gpg. That is hard on the USGS scale. It comes from 43 samples at 29 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 7.2 and 17.9 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
At 9.3 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. Because Jefferson Davis Parish straddles a decision line, check your own tap with a $10 test strip before you spend anything.
More on sizing a softener for your household.
From 0.1 to 32.7 gpg
The softest single sample on record in Jefferson Davis Parish was 1.4 mg/L and the hardest 560 mg/L, a 400-fold gap. The top quarter of sites read above 17.9 gpg and the bottom quarter below 7.2 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 9.3 gpg, rivers and lakes 3.4 gpg
43 groundwater samples from 29 wells put the median at 159 mg/L. 398 surface samples from 13 sites put it at 59 mg/L. In Jefferson Davis Parish the wells come out 5.9 gpg harder. Groundwater sits in contact with rock for years and picks up calcium and magnesium as it goes, so wells usually read harder. A utility here that draws from the river can deliver noticeably different water from a private well next door.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 203 lb of salt a year (6 bags of 40 lb, about $37), 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 $137 a year.
Sizing at 9.3 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 558 | 24,000 | 68 lb |
| 2 | 1,116 | 24,000 | 136 lb |
| 4 | 2,232 | 24,000 | 272 lb |
| 6 | 3,348 | 24,000 | 407 lb |
Jefferson Davis Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, Jefferson Davis Parish is number 26 of 64 counting from the hardest. Across the whole country it is harder than 48% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to Jefferson Davis Parish: Evangeline Parish (9.4), Lafourche Parish (9), St. James Parish (8.6).