The project involved upgrading the existing 92 ML San Juan Reservoir into a bigger reservoir with greater holding capacity of 111 million liters.
During construction, the old San Juan reservoir was demolished in phases to avoid disruptions in water supply. There were 3 equal chambers constructed, each with a capacity of 37 ML.
Built before the start of World War II in 1937, the old San Juan reservoir was used by the Metropolitan Waterworks and Sewerage System to supply mostly the western part of the metropolis. The new reservoir, inaugurated in 2012, now supports the increasing demand for additional supply and further boosts water supply reliability for Quezon City, San Juan, Mandaluyong and Makati.