Pollution Worsens Manila’s Flooding

When Typhoon Carina and the southwest monsoon submerged large parts of Metro Manila in July 2024, the floodwaters carried more than just debris. They dragged along over 600 tons of collected waste through the streets, a stark visual of a problem that goes far beyond rainfall. The connection between what we throw away and how quickly a city drowns is not incidental — it is structural.

Lawmakers have been blunt about the cause. During a House briefing in August 2025, Caloocan City Representative Edgar Erice stated plainly that Metro Manila’s flooding will persist unless its solid waste management system — which he described as the “worst in the world” — is fixed. The numbers back him up. Around 1.8 million tons of garbage go uncollected annually in the capital region, and much of it ends up in the very waterways that are supposed to drain rainwater. This is not a side issue to flooding. It is, according to multiple lawmakers who spoke at the briefing, the primary cause. For a deeper look at how pollution affects the country’s waters, you can read about pollution’s impact on Philippine seas.

How Garbage Turns Rain into a Crisis

The mechanism is straightforward but devastating. Metro Manila produces roughly 11,000 tons of waste every day, yet only an estimated 30 to 40 percent is collected. The rest sits in streets, vacant lots, and — critically — in the drainage network. When heavy rain hits, the canals and esteros that should channel water away are already choked with plastic and debris. The water rises, and the city floods.

This is not a problem that can be solved by bigger pumps or deeper drains alone. The waste has to stop entering the system in the first place. Rizal Representative Jojo Garcia, a former general manager of the Metropolitan Manila Development Authority (MMDA), echoed that garbage is the main culprit and urged the Department of the Interior and Local Government (DILG) to order barangays nationwide to clear waterways. He pointed to his own town’s success in reducing floods through such efforts as evidence that local action can work.

The Scale of the Waste Problem and Its Roots

The Philippines contributes an outsized share of the world’s ocean plastic. Citing a 2020 Bloomberg report, Erice noted that the country accounts for 34.7 percent of plastic waste in the world’s oceans, far exceeding other nations. That figure is not just an environmental statistic — it is a direct measure of how much material is bypassing the waste management system and entering waterways. Much of that plastic travels through urban drainage systems before reaching the sea, and it clogs those systems along the way.

The roots of the problem are not just about individual behaviour. Erice alleged that garbage collection in Metro Manila is monopolised by contractors who also own the dump sites, creating a system with little incentive to improve efficiency or expand coverage. He also criticised the Department of Public Works and Highways (DPWH) for suspending dredging operations for a decade, allegedly due to corruption. Whether or not those specific allegations hold, the outcome is measurable: waterways that should be deep enough to carry stormwater have been slowly filling with silt and garbage for years.

Marikina Representative Romero Quimbo offered a contrasting example. He shared that his city minimised flooding by clearing riverbanks of informal settlers, expanding river capacity, constructing flood protection walls, and building interceptor channels and water impounding structures. He also credited the Upper Wawa Dam for holding up to 20 million cubic meters of rainwater from the Sierra Madre, preventing overflow to Marikina and downstream areas. The lesson is that engineering solutions work, but they require consistent maintenance and political will — two things that have been in short supply at the regional level. For more context on how pollution accumulates in specific areas, see the discussion on pollution hotspots in the Philippines.

What Gets Missed in the Flooding Debate

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The public conversation about flooding in Metro Manila tends to focus on rainfall intensity, climate change, and the need for more drainage infrastructure. Those are real factors, but they miss a more immediate and actionable problem. Even a moderate rain event can cause severe flooding if the drainage system is already full of garbage. The debate often skips over the fact that the system is not just overwhelmed — it is blocked.

The Monopoly Problem in Waste Collection

Erice’s allegation that garbage collection is controlled by a small group of contractors who also own the dump sites points to a structural issue that is rarely discussed. If the same entity that collects waste also profits from its disposal, there is little financial reason to reduce the amount of waste going to landfills or to improve collection rates. The MMDA, he urged, should break this monopoly and open bidding for modern waste-to-energy and engineered landfill projects. Whether that specific solution is the right one is debatable, but the underlying point is hard to ignore: the current system has built-in incentives that work against effective waste management.

The Dredging Gap

The suspension of dredging operations for a decade is another factor that receives less attention than it deserves. Dredging is not glamorous, but it is essential. Rivers and canals naturally accumulate sediment over time, and that sediment reduces their capacity to carry water. When garbage is added on top of the sediment, the capacity drops even further. Erice proposed dredging all waterways as part of a three-pronged solution that also includes requiring mayors to ensure garbage removal and dismantling structures built over natural waterways. He claimed these measures could cut flood duration from three hours to 30 minutes. That is a bold claim, but it underscores how much of the flooding problem is man-made and therefore solvable.

The Role of Upstream Infrastructure

Quimbo’s suggestion to push the proposed Triple Dam in the Sierra Madre as a long-term flood control solution introduces a different angle. While waste management addresses the immediate clogging of urban waterways, upstream infrastructure can manage the volume of water coming down from the mountains. The Upper Wawa Dam already holds up to 20 million cubic meters of rainwater, and additional dams could provide more buffer. But dams are expensive, take years to build, and do nothing to solve the garbage problem in the city’s drainage network. They are a complement, not a replacement.

What Can Be Done About It

The solutions being discussed in Congress fall into three categories: fixing waste collection, clearing waterways, and building better infrastructure. Each requires a different level of effort and a different timeline.

Breaking the Collection Monopoly

Erice’s call for the MMDA to break the landfill monopoly and open bidding for modern waste-to-energy and engineered landfill projects is the most structural proposal on the table. If implemented, it would mean that garbage collection contracts are awarded based on performance rather than ownership of disposal sites. The process would involve the MMDA reviewing existing contracts, identifying conflicts of interest, and issuing new tenders with clear service-level requirements. For residents, the practical effect would be more consistent collection and less garbage accumulating in streets and waterways.

Barangay-Led Waterway Clearing

Garcia’s proposal is simpler and more immediate: order barangays nationwide to clear waterways. He cited his own town’s success as evidence that this works. The process involves barangay officials identifying clogged canals and esteros in their jurisdiction, organising clean-up drives with community participation, and coordinating with the local government for waste disposal. The key is enforcement — without it, the same waterways will be clogged again within weeks. The DILG would need to issue a directive and monitor compliance.

• 1
  Identify Blocked Waterways

  Barangay officials map all canals and esteros in their area, noting which are clogged with garbage or silt.

• 2
  Organise Community Clean-Ups

  Residents, local businesses, and civic groups are mobilised to remove waste from identified waterways.

• 3
  Coordinate Waste Disposal

  Collected garbage is transported to designated disposal sites, with the local government providing logistical support.

• 4
  Enforce Anti-Littering Ordinances

  Barangay officials and local police enforce fines and penalties for illegal dumping to prevent re-clogging.

Dredging and Infrastructure Investment

Erice’s proposal to dredge all waterways is the most expensive and time-consuming solution, but also the most impactful for flood duration. He claimed it could reduce flooding from three hours to 30 minutes. The process would involve the DPWH or MMDA contracting dredging operations for major rivers and canals, removing both silt and accumulated garbage, and then maintaining the depth through regular dredging schedules. This would need to be paired with the dismantling of structures built over natural waterways, which is politically difficult but necessary for water to flow freely.

Long-Term Infrastructure: The Triple Dam Proposal

Quimbo’s suggestion to push the proposed Triple Dam in the Sierra Madre represents a longer-term approach. These dams would capture rainwater before it reaches Metro Manila, reducing the volume that the urban drainage system needs to handle. The Upper Wawa Dam already provides this function, holding up to 20 million cubic meters. Additional dams would increase that capacity. However, this is a multi-year, multi-billion-peso project that requires environmental impact assessments, land acquisition, and construction. It is not a solution for next year’s rainy season. For more on how pollution affects the broader environment, see the article on coal plants and Filipino pollution woes.

Frequently Asked Questions

What to Watch for Next

The House briefing in August 2025 was part of a broader response to President Ferdinand Marcos Jr.’s call to eliminate corruption and substandard work in flood control projects. Whether that translates into actual policy changes — breaking the landfill monopoly, resuming dredging, and enforcing waterway clearing — remains to be seen. The solutions are not mysterious. They are known, they are debated openly, and they are within the government’s capacity to implement. The question is whether the political will exists to follow through. If this was useful, you might also want to read how river clean-up efforts are transforming waterways.

Sources

Filipino air choked by unregulated waste burning — Explores another consequence of poor waste management: the health impact of burning garbage in communities without collection services.

The cost of pollution to the Philippine economy — Examines the broader economic toll of environmental degradation, including flood damage and lost productivity.

Worst in the world waste management system worsens Metro Manila flooding, lawmakers say. BusinessMirror, 2025.

Amid flooding, groups call on PH to lead on plastics treaty. Greenpeace Philippines, 2025.