The liquid sludge water is produced from coagulation/filtration units and filtration operation of water treatment plant. The utilization of liquid sludge water from water treatment plant is an efficient way to save water resource. The potential problems in recycling the liquid sludge water are discussed in this paper from the aspects of its biological, physical and chemical properties. The microbiological safety of filtered water can be improved by recycling the liquid sludge water after coagulation and sedimentation or membrane filtration pretreatment. The status of utilization of the liquid sludge water at home and abroad is presented as well.