Philippines' Wawa Dam, Marikina River overflow: 'Hope it doesn't rain anymore'

Manila: Relentless rains are poised to submerge low-lying districts of the Philippine capital, with riverside communities near the Marikina River bearing the brunt.

As downpours persist and waterways choke with trash, the looming threat of widespread flooding hangs heavily over vulnerable neighbourhoods.

More than 1 million people had been affected while 6 deaths were recorded by the recent typhoon Crising (International code: "Wipha") alongside the southwest monsoon (locally known as "Habagat")

On Tuesday morning, July 22, 2025, the Marikina River overflowed amid ongoing heavy rains.

Marikina, downstream from the Sierra Madre Mountain range, is one of the 16 component cities of Metro Manila, the national capital region.

At 11:00AM on Tuesday (July 22, 2025), weather bureau Pagasa raised an orange warning over Metro Manila, signalling the risk of flooding in certain areas.

Monsoon rains are still ongoing, and authorities continue to carry out forced evacuations in low-lying areas as a precautionary measure. Residents are advised to stay alert and follow local advisories.

Widespread floods are expected in surrounding communities, prompting local governments to implement mandatory evacuation efforts.

Local government units (LGUs) are not only monitoring the water level of the Marikina River but also the smaller waterways, which are getting clogged with washed-in garbage.

Several areas in old Manila were also water-logged on Tuesday (July 22).

This causes these waterways to overflow, resulting in the flooding of some areas.

At 6pm on Monday (July 21), the Marikina River breached the 17-meter mark, triggering a second alarm in Marikina City, which means "preemptive evacuation" in affected areas.

Just before midnight on Tuesday (July 22), the water level breached the 18.5-metre mark — triggering a third alarm.

Classes were cancelled in the capital. Meanwhile, emergency workers were on hand — from the Bureau of Fire Protection and rescuers — to inform and help residents evacuate residents.

As of July 22, 2025, Wawa Dam in Rizal has reached and exceeded its critical (spilling) level due to continued heavy rains from the southwest monsoon, local media reported. 

On Monday afternoon (July 21), the dam's water level was reported at 135.58 metres — above its spilling level of 135 metres — resulting in overflow into the Marikina River and affecting areas downstream, including Pasig and Marikina. 

The Upper Wawa Dam, part of the Wawa Bulk Water Supply Project led by Prime Infra and WawaJVCo, is currently in the final stages of construction and set to begin commercial operations by the end of 2025. 

This dam is designed to supply up to 700 million litres per day and significantly boost Metro Manila’s water security, as well as help mitigate flooding downstream.

The dam has already started impounding water, with its key infrastructure like the pumping station energised and ready for integration with regional water supply and flood management systems.

Completion of the Upper Wawa Dam will make it the largest water supply infrastructure project in over 50 years and is intended to increase Manila Water Co. capacity by over 30%.

The Marikina River originates from the Sierra Madre mountain range and flows downstream through the Marikina Valley before emptying into the Pasig River. 

Specifically, the river's headwaters are in the Sierra Madre, near what is now Rodriguez (formerly Montalban), Rizal, and it flows southward through Marikina Valley, flanked by the Sierra Madre to the east and Quezon City to the west, before reaching Pasig City. 

The river's course through the valley makes Marikina City, and the surrounding area, susceptible to flooding from the river's runoff.