How hard is the water in Gwinnett County, GA?
5.4 grains per gallon
Optional: a softener helps, but plenty of homes skip it.
The median hardness measured in Gwinnett County, GA is 93 mg/L as calcium carbonate, which is 5.4 gpg. That is moderately hard on the USGS scale. It comes from 50 samples at 19 sites between 1993 and 2026, 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 4 and 6.4 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: high (how it is measured).
What to do next
At 5.4 gpg this is your call. Look for white film on glasses and crust on the shower head: if you see little of either, you can live without one. If you do want one, a 24,000-grain unit is enough, so ask for that size rather than a bigger one.
More on when a softener is not worth it.
From 1.2 to 8.4 gpg
The softest single sample on record in Gwinnett County was 20 mg/L and the hardest 144 mg/L, a 7-fold gap. The top quarter of sites read above 6.4 gpg and the bottom quarter below 4 gpg.
Wells 5.4 gpg, rivers and lakes 1.4 gpg
50 groundwater samples from 19 wells put the median at 92.9 mg/L. 4,736 surface samples from 60 sites put it at 23.5 mg/L. In Gwinnett County the wells come out 4.0 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 119 lb of salt a year (3 bags of 40 lb, about $21), 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 $121 a year.
Sizing at 5.4 gpg
| People | Grains a day | Unit | Salt a year |
|---|---|---|---|
| 1 | 324 | 24,000 | 39 lb |
| 2 | 648 | 24,000 | 79 lb |
| 4 | 1,296 | 24,000 | 158 lb |
| 6 | 1,944 | 24,000 | 237 lb |
Gwinnett County against the rest of Georgia
Among the 159 Georgia counties with data, Gwinnett County is number 22 of 159 counting from the hardest. Across the whole country it is harder than 32% of counties.
Softest in Georgia: Richmond County at 0.2 gpg. Hardest: Glynn County at 13.6 gpg. Closest to Gwinnett County: Terrell County (5.5), Whitfield County (5.7), Bartow County (5.2).