"Water" the term originated in Japan, corresponding to the water supply, drainage, named after the content is defined between the cleanliness of the water between water supply and drainage. In 1995 the Ministry of Construction promulgated the "Interim Measures for urban water facilities, " the water will be defined as: part of the quality of life of treated water purified complex to achieve "water of life indicators mixed water"(CJ25.1-89), can A range of non-potable water reuse. Although not suitable for drinking water, but it is less demanding on water quality can be used for a number of occasions.

　　Objects in the water reuse sub-municipal complex water, living water and industrial water complex. For example, in the city and the water can be used to wash the road, vehicles, toilets and green, or even fire. Of water scarcity, a large amount of water in these areas, with high-quality tap water is the waste of water, which provides for the use of water in the feasible space. Practice shows that the water use for environmental protection, water conservation, sustainable economic development can play an important role.

　　Water reuse in foreign countries has been widely used, including the extreme shortage of water resources in Israel, and the United States, Japan and other countries in the use of water has accumulated many successful experiences. Israel called the world's water use in the country 46% of the total sewage treatment direct return for irrigation, and about 20% of the remaining 33.3%, respectively, and recharge into the underground river, back to the end, is used for all aspects of indirect (Including irrigation). Urban sewage treatment facilities in the United States has been very sound, urban water reuse applications are already in mass production stage, especially in the arid climate of central and western regions.As early as 1962 the Japanese launched a study of water reuse, since the 80s from the 20th century strongly advocated the use of water and sewage in the waterways and between the specially set up in the waterways. And to encourage the setting channel system, the Japanese government established incentives, by reducing taxes, financing and grants and other means to promote them vigorously; the same time, also asked the new government agencies, schools, corporate offices and clubhouse, parks and playgrounds And other public buildings must be set in the waterways.
　　China in the "Plan ", "July" began during the study, water use, "Eighth" part of the petrochemical companies started during the test works, since the late 90s of the 20th century to promote the use, reuse of water in 2000 was officially Write "Tenth Five Year "Plan, that the country started in the water reuse project. At present, water reuse has been formed a certain scale, a number of serious water shortage in the northern cities such as Beijing, Tianjin and other cities, the water reuse project has been quite common. "Beijing in the construction of water management pilot scheme " provides that: in the city within the construction area of ​​2 million square meters of hotels, restaurants and construction area of ​​30,000 square meters of the other public buildings to be built without the necessary water facilities.　

　
　　一、Water reuse and its causes difficulties

 But it is worth noting that the current water reuse, there are many problems. First of all, water reuse is not wide enough range of applications, only some cities with serious water shortages, and most of the water project by the government to force the installation; Secondly, have been carried out in some areas of water reuse, water reuse Project operating in poor condition. Many residents of the community in the Beijing water reuse project idle for many years, causing a serious waste of investment. Complex reasons for this situation, both the technical issues, but also economic and institutional issues. First, the understanding. Some of the higher price, and areas of serious water shortages, government, businesses and residents already have the awareness of water reuse, and launched a productive practice. However, relatively rich in water resources, relatively low price of water south, the awareness of water reuse is still very weak, the public awareness of water is also very lacking, it is customary to be acceptable.

　The first，Construction problems. (1) Since the water system in the independent water supply systems, water reuse to carry out necessary requirement for building an alternative to the drainage system, making the water reuse system can only be used in new construction; (2) water Reuse technology is still evolving among some of the early water reuse system due to technical problems resulted in poor water quality, the cost is too high, resulting in the water reuse system idle and waste, but also reduces the update of water Reuse technology incentives; (3) water reuse is currently the main mode is "self", that district, the hotel's internal and independent construction of a water reuse project, due to the instability of water, reuse of smaller, Lead to underutilized facilities, water supply is very unstable and high cost. Some regions have set up a certain amount of the water company, but limited to the pipe network problem, transportation costs, has not been widely used. Although the company specialized in water treatment reduced the cost of water, but how will the water to the hands of users became a problem, the current solution is to build a new municipal water supply pipelines, water supply and bottled water car, obviously it would greatly Increases in the cost of water.
　The second，Price. Prices directly affect the demand for water. Present problems because of technical and scale make the cost of water reuse in the high number and small size in the water reuse project in the cost of water even more than the price of tap water. Tap water is a direct substitute for water, so water is no competitive advantage.
　The third，Regime. At present, China does not have a water reuse to adapt to the institutional system, including standards for water reuse, water regulation, water project investment. Our implementation of water reuse construction water quality standards is the existing "life miscellaneous water quality standards, " some indicators of the standard return than in developed countries has strict water quality standards. In this regard so many of the existing substandard water project; the other hand, limits the construction of water works to promote and popularize. In addition, the regulation of water back there with the absence of problems, in the absence of on-site routine monitoring and management in monitoring the situation, most of the construction of water facilities is actually running out of control, the user water requirements can not be guaranteed.