The Deep Tunnel Sewerage System (DTSS) project is an innovative and cost effective solution to meet Singapore’s long-term needs for used water collection, treatment and disposal. It is conceptualised as a means to relieve land use in land scarce Singapore and also to convey and treat used water reliably.

The first phase of DTSS consists of a pan-island deep tunnel sewer and a network of link sewers to convey used water by gravity to a large water reclamation plant at Changi for treatment before the effluent is being discharged through a deep sea outfall. The Project is scheduled for completion in 2008.

In future, the DTSS will replace the existing six water reclamation plants and about 130 pumping stations. It will free up prime land currently used by the existing plants and stations, as well as the buffer zones surrounding the plants. The area is estimated to be 1000 hectares which is equivalent to the size of two new towns in Singapore.

In the long run, due to economies of scale, it is more cost effective to implement DTSS than to continue to upgrade and expand existing plants.

The DTSS will form an integral part of the water loop, allowing PUB to channel used water to WRPs and then on to NEWater factories, where high grade reclaimed water is produced thus securing a sustainable source of water supply for Singapore. By collecting and treating every drop of used water, DTSS helps to “close the water loop”.By Public Utilities Board