In nature, the water in the sun and the gravity of the earth and the role of the movement of the non-stop movement, the natural water in the non-stop cycle. After the precipitation reaches the ground, through the inflow of river, river, lake, sea, reservoir, etc., or inflow to the formation, or by evaporation to the atmosphere. Natural cycle of water accounted for only 0.031% of the total amount of water on earth, the runoff and seepage accounted for about 0.003% for humans to meet the life and production of water, is a part of the social circulation system of a water supply and drainage.