On Monday, March 21, The Asian Development Bank (ADB) approved a $123.3 million loan for a new 6km water tunnel to help modernize Manila’s water supply, reducing the risk of shortages as demand for water rises in tandem with the city’s booming population. “The Angat transmission system provides more than 95% of Manila’s water but its existing tunnels are up to 75 years old and in poor condition, leaving the metropolitan area highly vulnerable to serious supply disruptions,” said Paul van Klaveren, Senior Urban Development Specialist with ADB’s Southeast Asia Department. “This assistance will allow the Metropolitan Waterworks and Sewerage System (MWSS) to build a fourth tunnel, clearing the way for it to upgrade and modernize its other existing tunnels and aqueducts to maximize and strengthen supplies.”
The MWSS is a government-owned corporation, supplying raw water for Manila, with two private companies holding distribution concessions. Demand for water has grown strongly to around 40 cubic meters a second, with the concessionaires largely able to meet demand in the past by sharply reducing nonrevenue water, or water that is produced but does not reach the customer due to system faults. However, with demand still increasing, the MWSS is planning to develop a major new water source, which is expected to be operational after 2021.
In the interim, there is an urgent need to rehabilitate the Angat system to avert a potential supply breakdown, and the MWSS has been carrying out improvements including the construction of a new aqueduct. The benefits of this aqueduct can only be fully achieved if a new tunnel is built to provide it with raw water.
The planned tunnel will be over 6km long with an internal diameter of about 4m, an intake structure at the Ipo reservoir, and a new transition basin at Bigte, along with connecting infrastructure. A key element will be structural measures to limit the impact of earthquakes and other hazards, as well as environmental degradation.
Capacity building support will also be provided to improve the skills of MWSS staff so that they can meet their management responsibilities for securing raw water supplies for the concessionaires.