SC has an area of 32,000 square miles or 20,480,000 acres. The average annual rainfall is about 4 feet. So that is about 80 million acre-feet of precipitation.

SC has an area of 32,000 square miles or 20,480,000 acres. The average annual rainfall is about 4 feet. So that is about 80 million acre-feet of precipitation. Converting from acre feet to gallons gives 26,000,000 million gallons of rainfall annually. Depending on hurricanes, it could be more, much more.