This is in addition to the city-state’s other main methods of ensuring water supply-importing, using reservoirs and desalinating seawater.
The core of the circulation system is the high-tech Changi Water Reclamation Plant located on the east coast of the city.
In Singapore, where land is scarce, part of the facility is underground—some as deep as 25 stories—and is supplied by wastewater that flows through a huge 48-kilometer (30-mile) tunnel connected to a sewer.
The site has a labyrinth of steel pipes, pipes, water tanks, filtration systems, and other machinery that can treat up to 900 million liters (237 million US gallons) of wastewater every day—enough to fill an Olympic-sized swimming pool every 24 hours for a year.
In one building, a network of ventilators was installed to keep the air fresh, even though the air was still filled with the smell of decay.
