In drinking water, excessive residual aluminum can harm human health severely, such as retaining foetus neurofibril development, leading to dementia and exhibiting dialysis osteo-dystrophy. In addition, excessive residual aluminum may have certain effect on the water distribution system. The World Health Organization and many developed countries have regulated the residual aluminum as a norm of drinking water quality and limited the respective maximum concentration level. Aluminum is present in all natural water, but the total residual aluminum in drinking water mainly comes from use of aluminum coagulants under improper operational conditions. Thus, optimizing the operational conditions or adopting other measures would reduce the total residual aluminum in drinking water.