The DTSS is a superhighway for used water management. It is a core water infrastructure which provides a cost-effective and sustainable solution to support Singapore’s continued growth and meet its long-term needs for used water collection, treatment, reclamation and disposal.

The DTSS uses deep tunnel sewers to convey used water entirely by gravity to centralised WRPs located at the coastal areas. The used water is then treated and further purified into ultra-clean, high-grade reclaimed water called NEWater, with excess treated effluent discharged to the sea.

DTSS Phase 1, comprising the North and Spur Tunnels, the associated link sewers, the Changi WRP and outfall, was completed in 2008. Two NEWater factories, located on the rooftop of the Changi WRP, were officially opened in 2010 and 2017 to facilitate large-scale water recycling.

The DTSS Phase 2 conveyance system comprises the South Tunnel which conveys domestic used water, the Industrial Tunnel for non-domestic used water and associated link sewers. Expected to complete by 2025, DTSS Phase 2 will extend the deep tunnel system to cover the western part of Singapore, including the downtown area and major upcoming developments such as Tengah Town and Jurong Lake District.

Under DTSS Phase 2, a NEWater factory to be integrated with the Tuas WRP will be built to facilitate water recycling, contributing to the goal of increasing NEWater supply from 40% to up to 55% of total water demand in the long term. Tuas WRP will also be integrated with NEA’s Integrated Waste Management Facility (IWMF), to harness potential synergies of the water-energy-waste nexus.

The completed DTSS will also streamline the used water network with three centralised collection and treatment points: Changi WRP in the east, Kranji WRP in the north and Tuas WRP in the west. Once Phase 2 is in place, the existing conventional WRPs at Ulu Pandan and Jurong, as well as intermediate pumping stations, will be progressively phased out and the land freed up for higher value development. The implementation of the entire DTSS will result in a 50% reduction in land taken up by used water infrastructure once it is fully completed, from 300 hectares in the 1990s to 150 hectares in the long term. The land freed up by DTSS is equivalent to about 214 football fields. 

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