North Charleston Water Hardness & Quality Report (2026)

North Charleston, South Carolina is served by Charleston Water System (CWS), the regional utility providing water to Charleston County including North Charleston, Mount Pleasant, and surrounding areas. The primary source is surface water from the Cooper River and Lake Moultrie, drawn via the Pinopolis Dam. Treatment occurs at the Hanahan Water Treatment Plant, which has a capacity of 140 million gallons per day, serving over 450,000 residents across Berkeley, Charleston, and Dorchester counties.

The watershed encompasses the Santee River Basin, feeding into Lake Moultrie and the Cooper River within the Atlantic Coastal Plain physiographic province. The geology features unconsolidated Quaternary sediments, sands, and clays, along with the underlying Tertiary Black Mingo Formation (Eocene age) with calcareous marls and limestones. These coastal plain formations contribute dissolved minerals including calcium and magnesium from limestone and shell deposits, resulting in a moderately mineralised supply shaped by the region's karst-like features and tidal influences.

Moderately hard water leads to moderate scale buildup in water heaters, dishwashers, washing machines, and pipes, reducing efficiency and lifespan by 20–30%. Fixtures may show spots and laundry can feel stiff. Regular maintenance includes vinegar descaling quarterly, installing drain screens, and flushing heaters annually; a water softener is recommended for households with hard water concerns. Treatment at the Hanahan Water Treatment Plant includes coagulation, sedimentation, filtration, and chloramination for disinfection; general compliance with regional standards is maintained with no notable contaminants highlighted in aggregators.