PUB is enhancing the used water sewer network. It has started the second phase of the Deep Tunnel Sewerage System (DTSS) – an underground sewerage superhighway that channels used water from sewers to centralised WRPs. Phase 1 of the DTSS was completed in 2008. By 2024, Phase 2 will extend the existing system to western Singapore with a 30 km-long South Tunnel linked to 70 km of sewers. A new Tuas WRP will be built and existing facilities will be progressively phased out to free up land for other developments.