The first stage of the Tseung Kwan O Desalination Plant will be commissioned tomorrow, meaning that it will start to provide a new water source that is not susceptible to climate change.

The Water Supplies Department said that on becoming fully operational, the plant will meet around 5% of the overall fresh water needs of Hong Kong, thanks to a water production capacity of 135,000 cubic metres per day.

The plant, together with the Pak Kong Water Treatment Works and the Tseung Kwan O Primary Fresh Water Service Reservoir, will supply drinking water to Sai Kung, as well as parts of East Kowloon and Hong Kong Island.

It is the first waterworks in the city to adopt advanced reverse osmosis desalination technology. Pre-treated seawater will pass through a membrane which filters out salt and impurities.

The desalinated seawater will then undergo post-treatment procedures to produce drinking water that fully meets Hong Kong Drinking Water Standards and is on a par with the quality of water supplied by other water treatment works in Hong Kong.

There will be real-time monitoring of the whole treatment process.

The department said it has started preliminary designs for the second stage of the plant and that an adjacent site is also earmarked for future expansion that would allow production capacity to meet 10% of the overall demand for fresh water in Hong Kong.