How hard is the water in Jefferson Parish, LA?
10.5 grains per gallon
A softener will pay its way here.
The median hardness measured in Jefferson Parish, LA is 180 mg/L as calcium carbonate, which is 10.5 gpg. That is hard on the USGS scale. It comes from 747 samples at 36 sites between 1990 and 2024, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 7.9 and 13.6 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
At 10.5 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. Because Jefferson 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 0.9 to 78.9 gpg
The softest single sample on record in Jefferson Parish was 15.3 mg/L and the hardest 1,350 mg/L, an 88-fold gap. The top quarter of sites read above 13.6 gpg and the bottom quarter below 7.9 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 1 gpg, rivers and lakes 11.2 gpg
5 groundwater samples from 3 wells put the median at 17.5 mg/L. 742 surface samples from 33 sites put it at 192 mg/L. In Jefferson Parish the rivers and lakes come out 10.2 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. A utility here that draws from the aquifer 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 230 lb of salt a year (6 bags of 40 lb, about $41), 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 $141 a year.
Sizing at 10.5 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 630 | 24,000 | 77 lb |
| 2 | 1,260 | 24,000 | 153 lb |
| 4 | 2,520 | 24,000 | 307 lb |
| 6 | 3,780 | 32,000 | 460 lb |
Jefferson Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, Jefferson Parish is number 24 of 64 counting from the hardest. Across the whole country it is harder than 53% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to Jefferson Parish: Vermilion Parish (10.9), Caldwell Parish (11.2), St. Charles Parish (11.4).