The La Mesa Dam and Reservoir is an earth dam whose reservoir can hold up to 50.5 million cubic meters and occupying an area of 27 square kilometers in Quezon City, Philippines. It was built in 1929 under the supervision of the construction firm Pedro Siochi and Company. It is part of the Angat-Ipo-La Mesa water system, which supplies most of the water supply of Metro Manila.The water collected in the reservoir is treated at the Balara Treatment Plant by the Manila Water, the private concessionaire of the Metropolitan Waterworks and Sewerage System, the government agency in charge of water supply, in Metro Manila's East Zone. 1.5 million liters of water pass through this reservoir every day. It is located in the La Mesa Watershed Reservation, the last forest of its size in the metropolis.