Seawater desalination, as a substitute and incremental technology for fresh water resources, is increasingly valued and supported. To be a feasible solution and an important way to solve the global water crisis in the future. According to statistics, by the end of 2010, more than 150 countries and regions around the world have carried out the work, desalination global seawater desalination project total investment of $34 billion, and the growth rate is 10-20% a year. It is expected to reach $56.4 billion in 2015. By the end of 2010, 68 sets of desalination plants had been built in China, but the problem of idle capacity and loss of industry in China's desalination industry was not uncommon.

On June 4, 2012, the national conference on water desalination held by the national development and reform commission was held in hangzhou, zhejiang province. To study and deploy the relevant work of the development of the "twelfth five-year" sea water desalination industry. Xie zhenhua, deputy director of the national development and reform commission (NDRC), stressed the need to clarify the strategic positioning of desalination, to achieve the development goals of the "12th five-year plan" and to provide relevant policy support.

Previously, on February 13, the state council general office document no. 13 "about speed up the development of the opinions of the seawater desalination industry", has been clear water desalination current development goal: by 2015, China has reached 2.2 million - 2.6 million cubic meters of water desalination capacity/day, on the island of new water supply of the contribution rate of 50% above, the contribution rate of new industries in coastal water shortage, water supply more than 15%; Seawater desalination raw materials, equipment manufacturing independent innovation rate of more than 70%; The establishment of a relatively complete industrial chain of seawater desalination, the key technology, equipment, materials research and development and manufacturing capacity to reach the international advanced level.

It can be said that the overall acceleration and large-scale development has become the two driving forces for the development of desalination industry, and the seawater desalination industry has an unprecedented opportunity.

However, in contrast, desalination engineering project has been put into operation in China, but have to let a person view on desalination, and the development of seawater desalination industry in China needs now is calm, need to be unified deployment, is a scientific outlook on development, rather than passion and speed. Seawater desalination must never again appear like sewage treatment, photovoltaic industry like "a swarm of bees" to the horse, and finally there is a "floor" situation.

However, there are three reasons for China's water desalination industry's idle capacity, loss of whole industry and lack of system planning.

Water: at present, the city waterworks is the guided subsidized by the government, and seawater desalination is according to calculate the production cost of market price, therefore, tap water and desalinated water has a big difference. The price of seawater desalination is about 8 yuan, while the price of city tap water is about 4 yuan. Therefore, if the downstream municipal water plant is to buy seawater desalination, who will come out of this price difference? Is it a citizen or a government subsidy?

Pipeline network: China's existing urban pipe network is generally cement and cast iron. The desalinated seawater is generally acidic, and the red water will appear after the iron pipe has been corroded for a long time. The color is not acceptable to the public, and the taste is not very good. If it is necessary to change the underground water supply pipe network into PVC pipe, who will bear the huge cost of pipeline network? If the cost of pipeline construction is to be calculated, the cost of desalination water is much higher than it is today.

Pollution: a tonne of concentrated brine is produced for each tonne of seawater desalinated, and a considerable amount of concentrated brine emissions are required to pollute the surrounding waters. If refined edible salt in large quantities, but in accordance with the "five-year plan", China's annual consumption of 6000 tons of salt, 2.6 million tons will be produced more than 100 million tons of salt, and caused a glut of salt industry.