Effect of coagulation pH on enhanced removal of NOM in treatment of reservoir water for drinking purposes has been investigated in this study. Raw water was collected at a local Waterworks of Singapore. Trials with different coagulation pHs and alum dosages were conducted in jar tests. NOM removal showed an up-and-down trend with increasing coagulation pH. The results showed that the optimum conditions for NOM removal were observed at a pH 5.2 and at alum dosage of 5 mg (Al)/L. NOM (in terms of DOC) removal of up to 45% and turbidity removal at 97% were noted during the tests conducted at the optimal conditions while NOM removal was 35% at the conventional coagulation pH 7.2. It was concluded that control of coagulation pH was critical for NOM removal in treatment of the reservoir water. (c) 2005 Published by Elsevier B.V.