The Deep Tunnel Sewerage System Phase 2 T-11 includes the design and construction of a 6km South Main Sewerage Tunnel, a 5.5km South Linkway Sewerage Tunnel, fifteen working shafts and related facilities. Two 3.0m diameter slurry TBMs and three 3.3m diameter slurry TBMs. The contract value is S$472.17 million.

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The deep tunnels are an integral part of the DTSS, conveying every drop of used water for treatment and channelling it for further reclamation into NEWater. As the backbone of NEWater production, the DTSS ensures the sustainability and resilience of the used water network to facilitate large-scale water recycling in Singapore and contributes to the goal of increasing the overall water recycling rate from 40% to up to 55% of total water demand in the long term. This network of 100 km of deep tunnels and link sewers will connect to the Tuas Water Reclamation Plant, which is expected to be completed in 2025.