Residential desalinated water supply cost reduction

Take Beijing (capital city of China) for example, it is said that by 2019 desalinated water will take a considerable share of Beijing water supply, check news from People's Daily Online: http://bj.people.com.cn/n/2014/0423/c82840-21055241.html. The current cost of desalinated water from one of the main suppliers is around 8 RMB per ton (roughly $1.28 USD per ton). Is there a big room to reduce the cost sharply including proper treatment of the brine?

Background: the current residential water price is 4 RMB per ton (roughly $0.64 USD per ton).