The Deep Tunnel Sewerage System (DTSS) is a cost-efficient and sustainable solution conceived by the Public Utilities Board (PUB) to meet Singapore’s long-term needs for used-water collection, treatment, reclamation and disposal.

DTSS uses deep tunnel sewers to convey used water by gravity to centralised water reclamation plants (WRPs) located at the coastal areas. The treated used water is further purified into ultra-clean, high-grade reclaimed water called NEWater or discharged to the sea through outfalls.

DTSS plays a crucial role in Singapore’s long-term used water system which comprises a network of link sewers leading to two major tunnels (Phase 1 and 2) criss-crossing Singapore with three large WRPs at the northern (Kranji), eastern (Changi) and western (Tuas) ends of Singapore, as well as outfall pipes.