This study reviewed optimum dosage rate of coagulant and ability to remove dissolved organic carbon withoutsedimentation in conventional water purification plant. It was confirmed that floc formated by pre-treatment process was brokenby impeller of booster pump. Optimum dosage rate of coagulant was 4 mg/L (as PACl 17%) for floc formation throughblend, coagulation and after passing through the pump when turbidity of raw water was less than 10 NTU. And average removalrate of dissolved organic carbon was 43% at that time. Maximum removal rate of dissolved organic carbon was 48%,even though coagulation rate was increased gradually until 8 mg/L (as PACl 17%). So removal rate of dissolved organiccarbon is not much improved even if dosage rage of coagulant increase. TMP of PVDF (polyvinylidene flouride) pressurizedMF process without pre-treatment operated at 0.54 bar and TMP of PVDF pressurized MF process with pre-treatment operatedat 0.41 bar.