How hard is the water in St. Charles Parish, LA?
11.4 grains per gallon
A softener will pay its way here.
The median hardness measured in St. Charles Parish, LA is 195 mg/L as calcium carbonate, which is 11.4 gpg. That is very hard on the USGS scale. It comes from 537 samples at 29 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 8.6 and 23.4 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 11.4 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 St. Charles 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 2.9 to 35.2 gpg
The softest single sample on record in St. Charles Parish was 48.8 mg/L and the hardest 602 mg/L, a 12-fold gap. The top quarter of sites read above 23.4 gpg and the bottom quarter below 8.6 gpg. So even here some sites draw water soft enough to need nothing at all.
What a softener would cost to run
For a household of 3, a 24,000-grain unit covers a week between regenerations. Expect about 249 lb of salt a year (7 bags of 40 lb, about $45), 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 $145 a year.
Sizing at 11.4 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 684 | 24,000 | 83 lb |
| 2 | 1,368 | 24,000 | 166 lb |
| 4 | 2,736 | 24,000 | 333 lb |
| 6 | 4,104 | 32,000 | 499 lb |
St. Charles Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, St. Charles Parish is number 21 of 64 counting from the hardest. Across the whole country it is harder than 56% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to St. Charles Parish: Caldwell Parish (11.2), Vermilion Parish (10.9), Jefferson Parish (10.5).