Introduction

Hidden beneath the historic Pinaglabanan Shrine, where Filipino revolutionaries bravely resisted Spanish colonial rule, lies El Deposito, one of the largest underground reservoirs in the world. Carved meticulously from volcanic tuff, this subterranean marvel once stored water transported from the Marikina River through the Carriedo Waterworks system, eventually supplying fountains and hydrants across Manila. The ambitious infrastructure project was designed by Genaro Palacios and constructed between 1878 and 1882, funded by a legacy left by Francisco Carriedo y Peredo, a Spanish philanthropist who, in 1733, bequeathed resources to provide Manila with a reliable water supply for its growing population of over 300,000.

Capacity & Structure

At its peak, El Deposito could hold an astonishing 56,000 cubic meters of water, enough to sustain the city for extended periods. Ingeniously designed ventilation shafts ensured the water remained fresh and uncontaminated. The reservoir stretches beneath the hill with a grand central channel that branches into 25 smaller chambers, each approximately five meters high and three meters wide. Its extensive network of cast-iron pipes, spanning over five kilometers, distributed life-giving water from the Marikina River to public fountains and hydrants throughout Manila, showcasing a level of engineering sophistication that was remarkable for the late 19th century.

Historical Significance

Beyond its utilitarian purpose, El Deposito became a silent witness to critical moments in Philippine history. During the Battle of San Juan del Monte on August 30, 1896, widely regarded as the first armed engagement of the Philippine Revolution, revolutionaries fought courageously to seize strategic positions, with the reservoir lying directly beneath the conflict zone. Its hidden tunnels and chambers provided strategic advantage and shelter in times of conflict, embedding the site deeply into the narrative of the nation’s fight for independence.

Other Uses

Over subsequent decades, El Deposito’s subterranean halls served diverse and sometimes grim purposes. Under American and Japanese occupation, portions were repurposed as an armory, a sanatorium for tuberculosis patients, and a military firing range. Recognizing its historical and cultural significance, the government later established a national shrine, inaugurated in 1973, to commemorate the bravery of Filipino revolutionaries and preserve this monumental engineering feat.

Decline & Restoration

Time and neglect gradually eroded El Deposito. By the early 21st century, the once-mighty reservoir had fallen into partial ruin, its chambers filled with debris and overgrowth. In 2016, an archaeological team conducted a meticulous assessment and excavation, revealing the reservoir’s complex structural details. Restoration efforts commenced under the National Historical Commission of the Philippines, though the initial reopening planned for 2020 was delayed by the COVID-19 pandemic. Finally, after years of careful conservation, El Deposito opened its doors to the public on November 30, 2023, offering visitors a tangible journey into Manila’s water supply heritage and the nation’s revolutionary past.