Waimalu, Hawaii, United States [CDP]; population was 29,967 in 1990; housing units was 10,613 in 1990; location is 21°24'N 157°57'W; land area is 5.91 square miles (3,781 acres); water area is 0.20 square miles (130 acres); FIPS code is 77750 [SourceCBP]