This study is done to find the alternatives to solve the water pollution problem. The common ways to treat polluted water is by using alum. However, the usage of alum as conventional coagulant had caused the formation of sludge that can pollute the water and also cause illness. Tamarind seed was chosen as the alternative because it is naturals, non-toxic, and 100% biodegradable sources. In this study, the research was done in two parts, there are tamarind seed extraction by using different extraction solutions and the jar test. The extraction solution that was used were sodium chloride, potassium chloride and distilled water. In jar test, synthetic turbid water with turbidity range from 200 to 220 NTU was used to determine the effectiveness of tamarind seed as natural coagulant. Form the results obtained, sodium chloride extract achieved the highest percentage or turbidity removal with the percentage 91.32% with the dosage 25mg/L at pH 6, while the distilled water extract obtained the lowest percentage of turbidity removal with the percentage 56.60 % with the dosage 30mg/L at pH 3. As a conclusion, tamarind seed can be used as a natural coagulant in the treatment of polluted water.
