Charleston, SC water hardness

Tap water hardness
57mg/L
3.3gpg
Soft

Reported by Charleston Water System (Sc1010001) · September 2025

SC typical
32 mg/L
EPA health violations since 2016
2
Data
Utility report

Charleston water measures 57 mg/L (3.3 gpg) of hardness, soft by USGS standards. The number comes from Charleston Water System (Sc1010001), dated September 2025.

Charleston on the hardness scale, with nearby cities
060120180240300360+SC typical 32Moncks Corner: 20 mg/LMoncks Corner 20Summerville: 26 mg/LSummerville 26Beaufort: 41 mg/LBeaufort 41Port Royal: 43 mg/LPort Royal 43Goose Creek: 46 mg/LGoose Creek 46Hanahan: 51 mg/LHanahan 51North Charleston: 53 mg/LNorth Charleston 53James Island: 58 mg/LJames Island 58Mount Pleasant: 59 mg/LMount Pleasant 59Hilton Head Island: 98 mg/LHilton Head Island 98Charleston 57mg/L as calcium carbonate060120180240300360+SC 32Summerville: 26 mg/LSummerville 26Goose Creek: 46 mg/LGoose Creek 46Hanahan: 51 mg/LHanahan 51North Charleston: 53 mg/LNorth Char. 53James Island: 58 mg/LJames Isla. 58Mount Pleasant: 59 mg/LMount Plea. 5957 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 57 mg/L, Charleston is 25 mg/L above the typical South Carolina figure of 32. Of the 10 nearest cities we track, 7 have softer water and 3 have harder. The range nearby runs from 20 mg/L in Moncks Corner to 98 in Hilton Head Island.

What 57 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

Nothing, as far as hardness goes. At 57 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for Charleston's water system

Charleston Water System (Sc1010001) · PWSID SC1010001

2 health-based violations since 2016

Serves about 278,771 people from surface water.

Health-based
2
Monitoring or reporting
0
Open now
0
20162017201820192020202120222023202420252026Lead and Copper Rule'16'18'20'22'24'26Lead and Copper Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Lead and Copper Rulecorrosion control and lead sampling22025Resolved

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Charleston water hard?

No. It measures about 57 mg/L (3.3 grains per gallon), which the USGS classes as soft.

What is the water hardness in Charleston in grains per gallon?

About 3.3 gpg. One grain per gallon equals 17.1 mg/L, so 57 mg/L divided by 17.1 gives 3.3.

Has the Charleston water system had EPA violations?

EPA records show 2 health-based violations for Charleston Water System (Sc1010001) since 2016, involving Lead and Copper Rule.

Nearby cities

All 58 cities in South Carolina

Hardness data: TapWaterData US Water Hardness (utility report, September 22, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.