This study evaluated the feasibility of a newly synthesized composite coagulant aid, SSG-S for turbidity removal in drinking water treatment. SSG-S was synthesized from rice starch and sesbania seed gum through the microwave irradiation method. The surface morphology of SSG-S was evaluated through scanning electron microscope (SEM). Compared with conventional rice starch, SSG-S provides more porous sites and longer chains for effective pollutant adsorption and bridging processes. Moreover, response surface methodology (RSM) revealed that the addition of SSG-S increased the turbidity reduction rate up to 96.3. In addition, the novel coagulant aid helped to reduce the dosage of alum, coagulant aid, and settling period by 6.7, 87.9, and 6.5 minutes (1.5 times quicker), respectively. © 2021 Malaysian Institute of Chemistry. All rights reserved.