Water supply applications. With the rapid development of economy and the improvement of people’s living standards, a large number of urban residential buildings, public buildings and tourism facilities have been constructed, and the demands for water and hot water supply have been updated. Water quality issues have received much attention. Galvanizing is commonly used as pipe in water supply projects. Because of its easy corrosion, the “red water” or “green water” phenomenon is difficult to improve the water quality, and because of the short service life of the leakage, it is predicted by experts that it will gradually withdraw from the historical stage, and plastic pipes, composite pipes and copper pipes It is not as good as stainless steel in terms of safety, reliability, hygiene, environmental protection and economical durability. Stainless steel is the best energy saving and environmental protection pipe for the water supply system with the best overall performance and the best quality for water supply. Thin-walled stainless steel has advantages of high strength, good toughness, no brittleness at low temperature, low coefficient of thermal expansion, no leakage, durability, no toxicity, no pollution, high cost-effectiveness, and reusability up to 100%. There are more and more applications in the project. Japan has been promoting the supply of stainless steel water pipes both inside and outside the building for 25 years. The complete stainless steel construction of the Tokyo water supply pipe ensures clean and hygienic water quality, greatly reducing the maintenance rate and leakage, saving water, and remaining intact after the Great Hanshin Earthquake. The legislation of Singapore stipulates that stainless steel pipelines must be used for urban water supply, and stainless steel pipe standards for the United States, Britain, and France. The use of stainless steel in water supply and water treatment projects is becoming increasingly common in developed countries in the world.