Bauxite tailing, the leftover materials from bauxite mining is in abundance in Indonesia. This material can be used as base material to produce PAC, a coagulant commonly used in water treatments. It has Al2O3 content of about 40%, and naturally is in the form of fine particles, thus it is economical and energy efficient to be processed into PAC. This innovation can reap a double benefits, i.e. utilizing the waste from growing bauxite mining sector, and may help in reducing dependency from currently imported PAC.