How hard is the water in St. James Parish, LA?
8.6 grains per gallon
A softener is worth it here.
The median hardness measured in St. James Parish, LA is 147 mg/L as calcium carbonate, which is 8.6 gpg. That is hard on the USGS scale. It comes from 101 samples at 5 sites between 1990 and 2022, drawn from every sampling site in the county, wells and surface water together.
How much it varies here
Half the sites came in between 5.4 and 10 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: medium (how it is measured).
What to do next
At 8.6 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 St. James 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 3.5 to 20.7 gpg
The softest single sample on record in St. James Parish was 60 mg/L and the hardest 354 mg/L, a 6-fold gap. The top quarter of sites read above 10 gpg and the bottom quarter below 5.4 gpg.
Wells 15.3 gpg, rivers and lakes 5.4 gpg
3 groundwater samples from 2 wells put the median at 262.3 mg/L. 98 surface samples from 3 sites put it at 92.3 mg/L. In St. James Parish the wells come out 9.9 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 188 lb of salt a year (5 bags of 40 lb, about $34), 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 $134 a year.
Sizing at 8.6 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 516 | 24,000 | 63 lb |
| 2 | 1,032 | 24,000 | 126 lb |
| 4 | 2,064 | 24,000 | 251 lb |
| 6 | 3,096 | 24,000 | 377 lb |
St. James Parish against the rest of Louisiana
Among the 64 Louisiana counties with data, St. James Parish is number 28 of 64 counting from the hardest. Across the whole country it is harder than 45% of counties.
Softest in Louisiana: Lincoln Parish at 0.1 gpg. Hardest: St. Bernard Parish at 53.9 gpg. Closest to St. James Parish: Terrebonne Parish (8.5), St. Mary Parish (8.2), St. John the Baptist Parish (8.2).