Soft water from mountains to coast
Greenville Water draws from Table Rock and North Saluda reservoirs in the mountains plus Lake Keowee. Columbia treats water from the Broad River and Lake Murray. Charleston Water System relies on the Edisto and on a Cooper River impoundment. All three supplies are soft, so South Carolina tanks rarely clog with scale; anode rods and humidity are the bigger concerns.
Licensing, flood zones and what jobs cost
The Department of Labor, Licensing and Regulation oversees plumbers through the Residential Builders Commission and the Contractor's Licensing Board, while cities and counties issue the permits. Along the coast, heaters in flood-zone homes often must sit above the design flood elevation. Coastal labor costs more than upstate labor, and Lowcountry installs above flood level add to it (replacement details).