Water authorities are planning to use seawater to meet rising demand.

According to a draft plan, Shenzhen city will launch a number of seawater desalination projects in power plants and tourism resorts along the east coast during the next five years.

"The power plants usually have stable and relatively cheap gas and electricity supplies, and can give out huge amount of heat energy, which are all suitable for distilling water," Wang Li, a senior engineer with the Shenzhen Water Bureau, told China Daily yesterday.

According to the plan, the country's first seawater desalination plant will be built inside Fuhuade Power Plant, which is located in Kuichong, eastern Shenzhen.

The plant is expected to produce 28,000 tons of fresh water a day.

"The fresh water produced by its own desalination system could at least satisfy the daily needs of the power plant," Wang said.

The local government also plans to build another two desalination plants, with daily capabilities of producing 10,000 tons of fresh water each.

According to the plan, they will be built in two tourism resorts, where demand for fresh water is growing.

However, it is still too early to commercialize these projects because of their high costs, Wang said.

"It will cost 5 to 6 yuan (about 70 US cents) to desalinate 1 ton of seawater, but currently the price for 1 ton of fresh water is little more than 2 yuan (25 US cents)," she said.

Although the desalination techniques have been improved and the costs are also expected to come down in the future, she believed seawater desalination could only serve as a supplement to the normal urban freshwater supply and, more importantly, to help cope with any emergency need for water.

"Since more than 80 per cent of the city's water supply is from the Dongjiang River (a major branch of the Pearl River), we have to be well-prepared for any emergency," Wang said.

She said sometimes seawater could be a good substitute for fresh water, for example when cooling down equipment in power plants and flushing toilets.

Last year, 7.3 billion tons of seawater was used to cool down equipment in power plants.

Peng Dongsheng, an expert with the Shenzhen Water Resources Planning & Design Institute, agreed that it was a good idea to use seawater to flush toilets but said the local government would have to make a major investment to build a separate water supply infrastructure.

According to the local government's draft plan, Yantian District in eastern Shenzhen may be the first to use seawater to flush toilets.

Editor: Yan