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Hong Kong water supply

Would you wash your car or flush your toilet with recycled waste water? Hong Kong government proposes new solution to city’s intense water use

  • Development Bureau and Water Supplies Department launch public consultation on using reclaimed water and grey water
  • Government’s Total Water Management Strategy wants to ‘ensure water security and sustainable development in Hong Kong’
PUBLISHED : Friday, 19 October, 2018, 5:59pm
UPDATED : Friday, 19 October, 2018, 10:24pm

Hong Kong residents could soon be flushing their toilets, washing their cars and irrigating their gardens with their own waste water, depending on the results of a public consultation.

The consultation – which the Development Bureau and Water Supplies Department began on Friday – proposes using reclaimed water, treated grey water and harvested rain water for flushing and non-potable uses, such as landscape irrigation, street cleaning, water features and car washing.

Reclaimed water is water which has been converted from treated sewage effluent, and grey water refers to used water discharged from baths, lavatory basins, wash basins and sinks.

The new proposal is part of the Total Water Management Strategy that the government suggested 10 years ago, to “ensure water security and sustainable development in Hong Kong in the face of climate change”, the authorities said.

Hong Kong is one of the world’s most intense water users. According to data from the city’s Water Supplies Department, direct water usage in Hong Kong has risen 17 per cent per person over the past two decades. At 220 litres of water a day in 2014, including the seawater used for toilet flushing, per capita water consumption is double the world average of 110 litres.

In her maiden policy address in October 2017, Chief Executive Carrie Lam Cheng Yuet-ngor announced a target of reducing per capita fresh water consumption in Hong Kong by 10 per cent by 2030.

Tap must be turned on Hong Kong’s waste of water

Under the proposal, the authorities will recycle waste water for flushing without charging the users, same as in the supply of salt water for flushing, which covers 85 per cent of the overall population. Areas in the north eastern New Territories, like Sheung Shui and Fanling, will be supplied with recycled water by 2022 onwards. By then, only about 10 per cent of the city’s population will use fresh water to flush their toilets.

At present, temporary mains water is also available for flushing on a “user pays” principle in some of the areas that are far from the sea, high in the mountains, or that are sparsely populated, including the North District, The Peak, the Southern District, Sai Kung and outlying islands. Usage exceeding 30 cubic metres by a household is charged at HK$4.58 per cubic metre.

Extra effort needed to stop Hong Kong wasting water

To avoid misuse, and to control the risk of cross-contamination, the government suggested colouring the recycled water, so that an immediate visual warning could be given in case of fresh water being contaminated.

Set to gauge public views with three public forums in 60 days until December 17, the new proposal does not touch on using the recycled water for potable usage, which has been adopted by other countries, such as Hong Kong’s long-term rival Singapore, and the city’s innovation role model Israel, for years.

Public members will be asked a total of 12 questions, such as whether they would agree to use recycled water for non-potable applications only, and whether recycled water used for non-potable uses other than flushing should be charged.