The inflluence of addition alum and filtration processes on water quality in water treatment Systems in the Desa Sumber Rejo has been researched. Quality parameters measured were pH, conductivity and TDS (total dissolved substance). The variables of this study was the addition of alum concentration (40 ppm, 80 ppm, 120 ppm, 160 ppm, 200 ppm) and variations in measurements every 5, 10, 15, 20, 2…