Abstract: Trihalomethanes (THMs) are one of the disinfection by-products (DBPs) groups that formed due to the reaction of organic matters with inorganic DPBs precursor and disinfectant. In this study, water (tap water, laboratory, river, Alur Ilmu and lake water, Engineering Lake), domestic (sewage) and industries wastewater (pharmaceutical and pulp and paper mills) were sampled in order to characterize and compare the level of THMs with the regulated limits of wastewater effluent and drinking water. The concentrations of total THMs (TTHMs) in raw and effluent of pharmaceutical and pulp and paper mills wastewater were 2589.24 and 1565.01 μg L–1, 2008.40 and 1519.63 μg L–1, respectively. The concentration of TTHMs in Engineering Lake was in range of 1481.54-1520.96 μg L–1, while in Alur Ilmu was around 2923.78-3724.05 μg L–1. It was also unexpected results that the levels of the TTHMs in laboratory tap water was in range of 1498.64-2288.46 μg L–1 which was higher than regulated limits for drinking water. Thus, further treatment of THMs is required either using chemical or biological treatments.