How hard is the water in Duval County, FL?
15.7 grains per gallon
A softener will pay its way here.
The median hardness measured in Duval County, FL is 268 mg/L as calcium carbonate, which is 15.7 gpg. That is very hard on the USGS scale. It comes from 649 samples at 92 sites between 1990 and 2017, 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 9.5 and 20.6 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 15.7 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 Duval County 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 0.2 to 173.5 gpg
The softest single sample on record in Duval County was 2.7 mg/L and the hardest 2,970 mg/L, a 1,100-fold gap. The top quarter of sites read above 20.6 gpg and the bottom quarter below 9.5 gpg. So even here some sites draw water soft enough to need nothing at all.
Wells 15.7 gpg, rivers and lakes 21 gpg
649 groundwater samples from 92 wells put the median at 268 mg/L. 3,716 surface samples from 164 sites put it at 359.5 mg/L. In Duval County the rivers and lakes come out 5.3 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 342 lb of salt a year (9 bags of 40 lb, about $62), 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 $162 a year.
Sizing at 15.7 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 942 | 24,000 | 115 lb |
| 2 | 1,884 | 24,000 | 229 lb |
| 4 | 3,768 | 32,000 | 458 lb |
| 6 | 5,652 | 40,000 | 688 lb |
Duval County against the rest of Florida
Among the 67 Florida counties with data, Duval County is number 19 of 67 counting from the hardest. Across the whole country it is harder than 71% of counties.
Softest in Florida: Washington County at 0.3 gpg. Hardest: Sarasota County at 32.2 gpg. Closest to Duval County: Orange County (15.8), Volusia County (16.1), Miami-Dade County (14.9).