With the example of the water supply engineering planning of small towns in southern china, the effects of town water consumption forecast, water resource selection, water site choice, pipe network planning on the present engineering planning of water supply were investigated. The analyses show that the water consumption forecast should adopt many kinds of methods to check each other, and finally determine a proper value. To ensure water yield of source water reliable and water quality to meet the requirements are the first principle of the water resource selection. The location of water plant...