Waikapu is a census-designated place in Maui County, Hawaii, United States. The population was 3,437 at the 2020 census. Waikapu is located at 20°51′10″N 156°30′36″W / 20.85278°N 156.51000°W. According to the United States Census Bureau, the CDP has a total area of 11.0 square miles, of which 11.0 square miles is land and 0.04 square miles, or 0.…Waikapu is a census-designated place in Maui County, Hawaii, United States. The population was 3,437 at the 2020 census. Waikapu is located at 20°51′10″N 156°30′36″W / 20.85278°N 156.51000°W. According to the United States Census Bureau, the CDP has a total area of 11.0 square miles, of which 11.0 square miles is land and 0.04 square miles, or 0.18%, is water.