【正文】 watersaving should be first. Within the bearing capacity of water resource and water environment, on the premise of ply the law of social development and water supply, we ought to carry out propaganda education about the consciousness of watersaving, perfect relevant legal system, prehensive use various conservation measures, and develop new technology. These methods can not only alleviate the contradiction between urban water supply and demand in a certain extent, also can reduce wastewater, and achieve good social and environmental benefits. REFERENCES [1] He Jianping, Watersaving Technology about Water Supply and Drainage in Building, Shanxi Architecture, , , . [2] Liu Zhenyin， The Discussion of Watersaving Technology about Water Supply and Drainage in Building， Water amp。s Ministry of Construction and the other four ministries jointly issued a document, the document required that the cold galvanized steel pipe was banned used as the water supply pipes of newlybuilt residences in national urban since June 1st, 2020. Based on the local conditions, the hot galvanized steel pipe is gradually prohibited to use and the latemodel pipe is promoted to use. In the construction’s water supply system, plastic pipes mainly consist of low plastic rigid polyvinyl chloride pipe (PVCU), chlorinated polyvinyl chloride pipe (PVCC), highdensity polyethylene pipe (HDPE), crosslinked polyethylene pipe (PEx), polypropylene pipe (PPR), polybutylene pipe (PB) and acrylonitrilebutadienestyrene pipe (ABS), etc. Composite pipes include AluminiumPlastic Composite pipes， plasticcoated steel tube, steelplastic posites pipe，etc. Metal pipes have copper pipes and stainless steel tube, etc. Compared with Galvanized steel pipes, plastic pipes have advantages in economy. Although the cost of Copper pipes and stainless steel tube is higher, the mean life may last longer and also can be used for hot water system. So we had better consider 670669the construction’s function, property, specification, the level and water supply before choose the appropriate highquality water supply pipes. The valve is the most mon accessory in building water supply and drainage, whose types and level of quality is the key of affecting watersaving. Generally speaking, the globe valves shut tighter than gate valves, and gate valves shut closer than butterfly valves. Hydraulic valves overe the large size of float valves, and overe the overflow and other disadvantages caused by plug stuck。 water conservation。 adopting watersaving waterdispensing fixtures and sanitary ware。 2020 IEEEDOI 669668Reducing Valve can reduce dynamic pressure, static pressure。 scientific research institution can save water around 40%。 Wastewater Engineering, Vol. 34 2020, . [5] Tan Chunan, The Study of Reuse of Reclaimed Water in Building and the Rationality of Technical and Economic. [D], Dalian University of Technology, 2020, . [6] Xiong Jiaqing, Rational Exploiting and Using Water Resource of Green Human Settlement.[D], Xi’an University of Architecture and Technology, 2020, . 672671。 and at the same time the emissions will reduce 35% ~ 50%。Although the code makes certain restrictive provision for the maximum pressure of water supply fittings and service pipe, this is considered from preventing the damage caused by high pressure of water supply fittings not from the angle of preventing overpressure flow. An experimental result of a watersaving tap shows that the maximum flow rate is L/s when tap fully open, the corresponding dynamic pressure is MPa and hydrostatic pressure is MPa. According to the rated flow q = 0. 15 L/s which is regarded as the standard, the flow rate when watersaving tap fully open is 3 times of the rated flow. In another m