WSD - Water Conservation - Seawater for Flushing

Part of a simple seawater flushing system constructed in early 1960

Seawater for flushing has been introduced in Hong Kong since the late 1950's. Up till now, Hong Kong is one of the few places extensively applying seawater for flushing. The use of such a sustainable water resource continues to play an important role in Hong Kong's water resource management. Currently, a total of 300 mcm per annum of seawater is supplied, conserving an equivalent amount of fresh water which is about 20% of the total water consumption in Hong Kong.

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Hong Kong has won international recognition for its leading role and success in making use of seawater for flushing to save fresh water resources. In recognition of the success in making extensive use of seawater for flushing, Water Supplies Department (WSD) was presented with the 2001 Chris Binnie Award for Sustainable Water Management by the Chartered Institution of Water and Environmental Management (CIWEM) in UK in April 2001. The department’s seawater flushing system was the first winner of the Chris Binnie Award outside Europe.

Effort towards extending the use of seawater for toilet flushing

WSD successfully extended the coverage of the seawater supply network for flushing from below 80% to 85% of the population for further reduction of fresh water demand. At present, seawater flushing has been available to buildings in Northwest New Territories (including Tuen Mun East, Hung Shui Kiu, Tin Shui Wai and Yuen Long Town Centre) and Pok Fu Lam.

WSD will further study the expansion of its seawater flushing system in a cost-effective manner, with Tung Chung as the next target area. WSD also target at expanding the network coverage of using seawater and recycled water for flushing from 85% of the total population to 90% in the long run in order to further reduce the fresh water demand for flushing.

Seawater has a high salt content. Will the pipes corrode or busts after conversion to seawater for flushing?

The plumbing materials used in flushing systems approved by the Water Authority since 1960s have already been designed to be resistant to salt water corrosion. There will not be any problem with the maintenance of the inside service after conversion to seawater for flushing. In fact, the seawater will be treated to meet the requirements set by the WSD before delivery to consumers for flushing.