Charleston Water Hardness & Quality Report (2026)

Charleston Water System is an independent municipal water and wastewater utility serving the greater Charleston area, including Charleston proper and surrounding communities in Charleston County, South Carolina, with approximately 224,157 residents served. The system sources water from surface water reservoirs and operates treatment facilities to deliver safe drinking water. The utility's main office is located at 103 St. Philip Street, Charleston, SC 29403; customer service is available at 843-308-8200, and annual Consumer Confidence Reports are published at charlestonwater.com for public review.

The supply area lies within the Atlantic Coastal Plain watershed, characterized by Cretaceous-age sediments overlain by Quaternary deposits of sand, silt, and clay. The region's geology consists primarily of unconsolidated coastal plain materials rather than the hard limestone formations found inland, producing a moderately hard water supply. The interaction of surface waters with sandy and clayey aquifer materials — alongside the ongoing challenge of saltwater intrusion management in the Lowcountry — further shapes the mineral character of the treated supply.

At moderately hard classification, Charleston's water causes noticeable scale buildup in kettles, coffee makers, and water heaters over time, reducing soap and detergent efficiency; residents with high-use appliances — particularly dishwashers and washing machines — may experience reduced lifespan and performance. A water softener is often recommended, though many residents manage through regular descaling maintenance. Testing from December 2023 detected PFOS (perfluorooctanesulfonic acid) at 5.56 parts per trillion, exceeding the EPA's threshold of 4 ppt; the water may also contain benzene, nitrate and nitrite, and alachlor. Residents are encouraged to consult the latest analytical results at charlestonwater.com.