How hard is the water in Williamsburg County, SC?

1.2 grains per gallon

You do not need a softener here.

The median hardness measured in Williamsburg County, SC is 21 mg/L as calcium carbonate, which is 1.2 gpg. That is soft on the USGS scale. It comes from 192 samples at 20 sites between 1990 and 2026, drawn from every sampling site in the county, wells and surface water together.

How much it varies here

Half the sites came in between 1.1 and 1.5 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

You can skip the softener. At 1.2 gpg the most a softener would fix is the odd water spot. If a salesperson in Williamsburg County says otherwise, ask to see their reading in grains per gallon and compare it with this one.

More on when a softener is not worth it.

From 0.2 to 2.1 gpg

The softest single sample on record in Williamsburg County was 3.6 mg/L and the hardest 36.5 mg/L, a 10-fold gap. The top quarter of sites read above 1.5 gpg and the bottom quarter below 1.1 gpg.

Wells 0.4 gpg, rivers and lakes 1.3 gpg

7 groundwater samples from 3 wells put the median at 6 mg/L. 185 surface samples from 17 sites put it at 22 mg/L. In Williamsburg County the rivers and lakes come out 0.9 gpg harder. Here the surface water reads harder than the wells, which often points to streams fed by limestone springs or irrigation return flow. The two sources are close, so the county figure should hold whichever one your tap is on.

Williamsburg County against the rest of South Carolina

Among the 46 South Carolina counties with data, Williamsburg County is number 23 of 46 counting from the hardest. Across the whole country it is harder than 9% of counties.

Softest in South Carolina: Aiken County at 0.2 gpg. Hardest: Georgetown County at 15.2 gpg. Closest to Williamsburg County: Calhoun County (1.2), Cherokee County (1.1), Clarendon County (1.1).