Singapore Deep Tunnel Sewerage System

Singapore’s Deep Tunnel Sewerage System (DTSS) will completely replace the tiny island nation’s wastewater infrastructure with a network of tunnels, pipelines, water reclamation plants and ocean outfalls. 


  • Singapore


  • Singapore Public Utilities Board

Project Status

  • Completed in 2008

One of the most ambitious wastewater management programs in the world, the $3.65 billion DTSS will allow Singapore to accommodate an expected population increase from 4.5 million to 5.5 million, reuse wastewater in beneficial ways, and redevelop land no longer needed for sewerage works. 

For the Public Utilities Board (PUB) of Singapore, WSP, in joint venture, provided conceptual engineering, preliminary design and program/construction management services for the project. The joint venture performed conceptual and preliminary design for the entire new wastewater infrastructure, which includes north and south systems. 

For the north system, which was completed in 2008, WSP assisted PUB with tender documents for the design of the link sewers, the new Changi water reclamation plant and the Changi outfall, and provided program management for the construction of 30 miles (48 kilometers) of tunnels completed under six design/build contracts involving eight tunnel boring machines and contractors and consultants from 11 countries. 

“The Deep Tunnel Sewerage System is an integral part of Singapore’s water management as it allows every drop of used water to be collected, treated, and further purified,” said PUB’s Chief Executive, Khoo Teng Chye, upon accepting the Water Project of the Year award at the Global Water Awards in Zurich, Switzerland, in April, 2009. 

The project also received a Prestigious Engineering Achievement Award from the Institution of Engineers Singapore and an Outstanding Engineering Achievement Award from the Association of Southeast Asian Nations.