In order to use alum in large numbers for the treatment of low turbidity water, a novel method has been used to treat low turbidity water using bentonite with a reduced amount of alum. Given that bentonite has a negative charge, it is added to the raw water to give the blocks weight. The weight is then added by joining the blocks together to create massive blocks that settle more quickly. In addition to providing a large surface for organic compound adsorption, it increases the suspension's weight and particle density. There are between 10 and 50 mg/l of bentonite clay utilized. In the Karbala water treatment plant, the effectiveness of the water quality index (WQI) at turbidity 20NTU using alum alone was subpar (71.16 percent). Under the same circumstances, the pilot plant's WQI efficiency was equally low (72 percent ). The turbidity of the water was increased to 120 NTU when bentonite was used in the pilot plant, increasing the efficiency of WQI to 97.2%. When bentonite was added to the water, the turbidity was increased to 200 NTU and the WQI efficiency was increased to 98.9%. The usage of bentonite produced a high level of WQI efficiency and a cheap substance free from infections or negative effects.