The mile 10 Langat Treatment Plant draws its raw water from the upper reaches of Sg. Langat. Flow in the river was regulated by the Langat impounding reservoir. Due to the prolonged drought in 1997, the storage in the Langat impounding reservoir was drastically draw down. Plant production was reduced as much as 50% of its normal output, causing great difficulties and inconveniences to the affected supply areas in Cheras, Ampang Ulu and parts of Kuala Lumpur.
In order to augment the yield in Sg. Langat, it was proposed to transfer 70 Mld (15 Mgd) raw water from the Semenyih impounding reservoir to Sg. Gemi, a tributary of Sg. Langat. The yield of Sg. Semenyih at the Semenyih Intake had been increased by 70 Mld (15 Mgd) under the Phase 1 of the project i.e. Projek Memindahkan Air Dari Tasik Ke Sungai Semenyih.
Due to the satisfactory performance in implementing the Phase 1 project, Premier Ayer-Asia Baru Consortium was again selected to undertake the project on turnkey basis.
The works proposed by the Consortium include : –