The coagulation and antimicrobial efficiency of Garcinia kola at different concentrations on turbid surface water samples collected from Ogbor Hill River in Aba was studied. Phytochemical analysis showed alkaloid content of 2.11±0.04% while saponin, flavonoid and tannin contents were 0.34±0.04%, 2.16±0.03% and 0.14±0.02%, respectively. Phenol content was 1.65±0.01%. The physicochemical and microbial analysis indicated that the water sample had temperature of 30.5±0.10 ℃, pH of 7.4±0.20, total dissolved solids of 161.54±1.13 mg/L, turbidity of 31.64±0.08 NTU, electrical conductivity of 221.4±0.35 μS/cm, biochemical oxygen demand of 5.87±0.03 mg/L, chloride content of 0.28±0.02 mg/L, nitrate content of 248.6±0.27 mg/L, nitrite content of 1.86±0.04 mg/L, 12.00±1.00 MPN/ml of Total Coliform, (7.67±1.00) x 102 CFU/ml of E. coli, (10.33±1.15) x102 CFU/ml of faecal streptococcus, (15.67±2.52) x 102 CFU/ml of Staphylococcus aureus and too numerous to count (TNTC) for total heterotrophic bacteria. However, microbial reduction after treatment with Garcinia kola seed extract at different concentrations ranged from 41.67–75.00% for total coliform, 34.81–73.92% for E. coli, 12.87-70.96% for Faecal streptococcus, 36.18–68.09% for Staphylococcus aureus and 45.30–65.81% for total heterotrophic bacteria. Garcina kola seed is non-toxic and does not significantly affect the pH and conductivity of the treated water.