A desalination facility which will become operational on December 22 can meet up to five percent of the territory's overall fresh water demand, the government says.

Authorities on Thursday said the first stage of the Tseung Kwan O Desalination Plant - the first in Hong Kong with advanced reverse osmosis desalination technology - will provide a new and stable water source that is "not susceptible to climate change".

"Upon entering into full operation, the [plant] will meet around five percent of the overall fresh water demand in Hong Kong with a water production capacity at 135,000 cubic metres per day," a Water Supplies Department spokesperson said.

"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."

The department added that a site nearby has been earmarked for future expansion, which could meet around 10 percent of the SAR's demand for fresh water.