Upper Wawa Dam Strengthens Rizal’s Flood Defense and Water Future

The Upper Wawa Dam has once again demonstrated its vital importance to Rizal Province and Metro Manila—not only as a major water source, but as a powerful shield that protects communities during severe weather. Operated by Manila Water subsidiary WawaJVCo, the dam is a landmark development built to secure clean, reliable water for millions while also playing a significant role in disaster resilience.

As the largest new water source developed in more than 50 years, the Upper Wawa Dam is designed to deliver up to 710 million liters of raw water per day, supporting approximately 3.5 million Filipinos across Metro Manila and nearby provinces. Its strategic location and engineering allow it to augment the region’s water supply year-round, addressing both present demands and long-term sustainability.

But its impact extends beyond water security. When Typhoon Uwan battered Metro Manila and Rizal, the Upper Wawa Dam became a crucial line of defense. Within just 30 hours, the reservoir level surged by 10 meters following 110 mm of rainfall at the dam site. Despite this rapid rise, the dam effectively reduced downstream flooding by as much as 99.5%, protecting the communities of Montalban, San Mateo, and Antipolo City. During the typhoon, it absorbed and stored an impressive 33.7 million cubic meters of stormwater—volume that would otherwise have flowed directly into low-lying areas.

WawaJVCo General Manager Joe Costales emphasized the dam’s dual purpose, noting that its robust engineering ensures both safety and sustainability. Built with a 262-square-kilometer watershed and a reservoir capacity of 120 million cubic meters, the structure incorporates advanced features such as a stepped chute and stilling basin. These dissipate water energy and reduce turbulence, allowing controlled releases that minimize erosion and mitigate flooding risks.

Designed under globally recognized standards—including ICOLD and USACE—the Upper Wawa Dam meets the highest benchmarks for stability and performance even during extreme events like floods and earthquakes.

Local leaders continue to recognize its indispensable role. Montalban Mayor Ronnie Evangelista praised the dam as a “game-changer” for Rizal, highlighting how it delivers both water security and flood protection—proving that forward-looking infrastructure can uplift communities while keeping them safe.