Coagulation-flocculation is the key process of water treatment in water turbidity removal. However, the usage of inorganic coagulants has raised awareness of researchers due to the threat possess on human health and environment. Therefore, studies in natural coagulant and modification of natural coagulant have raised various interest of researchers. Natural coagulants are widely available and non-toxic that can be obtained from animal, fungi, bacteria, and plant. Preliminary studies of plant-based natural coagulant aid, Hylocereus undatus in synthetic turbid water was also conducted. Remarkably, the usage of H. undatus with the mixture of ferric chloride has achieved a turbidity removal of 93.03. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.