The project to use seawater for flushing toilets was initiated 50 years ago, and has helped to ensure that the city is able to meet its water demands. Since its launch, the system has expanded and now comprises 45 service reservoirs, 40 pumping stations and over 1,400km of pipes with corrosion protection. The seawater is available using a dual reticulated water supply; it’s also given free of charge to all consumers.

The fixed asset cost of the seawater infrastructure, estimated at $737m by the Water Serviced Department of Hong Kong, has been a success. Currently, 22 percent of the total municipal water demand is met by seawater. Due to seawater’s reduced need for treatment and conveyance, the city benefited from lower energy use. Overall the project has resulted in a volumetric impact of 271,000,000m3/year.