The 24-hour rainfall record for the state of South Carolina is 14.80 inches observed at Myrtle Beach (Horry County) on September 16, 1999 is a result of Hurricane Floyd.
Previously listed record of 17.00 inches at Antreville on August 27, 1995 (Tropical Storm Jerry) was incongruent with other observations in the area, and all reliable evidence pointed to a much smaller 24-hr value.
Source: Hurricane FLoyd | WikiMedia