This study is focused on manganese (Mn(II)) removal by potassium permanganate (KMnO4) in surface water. The effects of bicarbonate on Mn(II) indicated that bicarbonate could remove Mn(II), but it was not effectively. When 0.5 mg/L of Mn(II) was dissolved in tap water, the addition of KMnO4 as much as KMnO4 to Mn(II) ratio is 0.67 satisfied the drinking water regulation for Mn (i.e. 0.05 mg/L), and the main mechanism was oxidation. On the other hand, when the same Mn(II) concentration was dissolved in surface water, the addition of KMnO4, which was the molar ratio of KMnO4/Mn(II) ranged 0.67 to 0.84 was needed for the regulation satisfaction, and the dominant mechanisms were both oxidation and adsorption. Unlike Mn(II) in tap water, the increasing the reaction time increased Mn(II) removal when KMnO4 was overdosed. Finally, the optimum conditions for the removals of 0.5 - 2.0 mg/L Mn(II) in surface water were both KMnO4 to Mn(II) ratio is 0.67 - 0.84 and the reaction time of 15 min. This indicated that the addition of KMnO4 was the one of convenient and effective methods to remove Mn(II).