How hard is the water in St. Landry Parish, LA?
15 grains per gallon
A softener will pay its way here.
The median hardness measured in St. Landry Parish, LA is 256 mg/L as calcium carbonate, which is 15 gpg. That is very hard on the USGS scale. It comes from 22 samples at 21 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 10.5 and 20.4 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: medium (how it is measured).
What to do next
At 15 gpg a softener pays its way here. Before you buy, check the quoted unit's grain capacity against the sizing table below, and ask whether it regenerates on demand, which uses less salt than a timer. Call your utility for its own report if you are on city water.
More on sizing a softener for your household.
From 0.9 to 29.8 gpg
The softest single sample on record in St. Landry Parish was 15.1 mg/L and the hardest 510 mg/L, a 34-fold gap. The top quarter of sites read above 20.4 gpg and the bottom quarter below 10.5 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 15 gpg, rivers and lakes 4.9 gpg
22 groundwater samples from 21 wells put the median at 256 mg/L. 440 surface samples from 10 sites put it at 84 mg/L. In St. Landry Parish the wells come out 10.1 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 327 lb of salt a year (9 bags of 40 lb, about $59), 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 $159 a year.
Sizing at 15 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 900 | 24,000 | 110 lb |
| 2 | 1,800 | 24,000 | 219 lb |
| 4 | 3,600 | 32,000 | 438 lb |
| 6 | 5,400 | 40,000 | 657 lb |
St. Landry Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, St. Landry Parish is number 17 of 64 counting from the hardest. Across the whole country it is harder than 69% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to St. Landry Parish: Franklin Parish (15.7), Iberia Parish (14), Concordia Parish (16.1).