Number One! Pasig River Is World's Biggest Source of Ocean Plastic Waste

And one-third of ocean plastic inputs come from the Philippines.

ocean plastic pollution
PHOTO BY Shutterstock

( For a country that's highly dependent on the ocean for food, transport, and livelihood, you would think that the Philippines would be one of the world's biggest advocate for marine conservation. As it turns out, this isn't the case. In a 2021 study, it was found out that the Pasig River in Metro Manila accounts for 6.43% of global river plastic that, of course, eventually end up in our ocean. Moreover, seven of the top 10 rivers that pollute the world's oceans are all found in the Philippines, making our country the top producer of ocean plastic waste—36% of it to be exact.

The research article titled "More than 1,000 rivers account for 80% of global riverine plastic emissions into the ocean" was published on April 30 on the American Association for the Advancement of Science's ScienceAdvances. It's a joint study of enviornmental scientists from Netherlands, Germany, and New Zealand. It was also synthesized in a May 1 article released on Our World in Data.


Previous research suggested that the world's ocean plastic pollution only come from a handful of rivers, which are mostly river basins. These studies relied on the idea that large bodies of water with large populations and poor waste management practices are the only culprits when it comes to plastic inputs to the ocean. As it turns out in the research, higher-resolution data also needed to be studied, including wind and precipitation patterns, river discharge into the ocean, proximity of populations to the river, distance to the ocean, slope of the terrain, and types of land use. With this, smaller rivers around the world were also considered.

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Share of Ocean Plastics from emitting rivers
PHOTO BY Website/Our World in Data

It was observed that the rivers that largely contribute to ocean plastic pollution have four characteristics:

  • Plastic pollution is dominant where the local waste management practices are poor.
  • They tend to have cities nearby.
  • They have high precipitation rates (meaning plastics washed into rivers, and the flow rate of rivers to the ocean was high).
  • Not only are they close to the cities, but they're also close to the coast.

Pasig River, as we know, is in the middle of the Philippines' most populated region. It connects Laguna de Bay to Manila Bay, all while passing through Taguig, Pasig, Mandaluyong, Makati, and Manila. Water from Marikina River, Taguig River, San Juan River also goes into it; until it reaches Manila Bay, which eventually flows to the West Philippine Sea. You can just imagine all the trash that come from the Philippines' urban center and into the ocean.

Aside from the Pasig River, other Philippine rivers that made it to the list are:

  • #4: Tullahan River (north of Manila)
  • #5: Meycauayan River (Bulacan)
  • #6: Pampanga River (second largest river in Luzon)
  • #7: Libmanan River (a tributary of Bicol River)
  • #9: Rio Grande de Mindanao (second largest river in the Philippines)
  • #10: Agno River (from the Cordilleras and into the West Philippine Sea)
2019 Share of global plastic waste emitted to ocean
PHOTO BY Website/Our World in Data

The study also had three observations on how countries around the world contribute to ocean plastic waste:

  • "Rich countries produce much more plastic waste per person than poorer countries." The United Kingdom for example, generates twice as much plastic waste compared to the Philippines.
  • But the caveat is that "rich countries" have the means to "incinerate, recycle, or send [trash] to well-managed landfills." Recovering countries, like the Philippines and India, have poorer waste management infrastructure like open landfills.
  • The probability of mismanaged plastic waste entering the ocean is much higher in the Philippines, Malaysia, Sri Lanka, China, and India.

With water making up about 71% of the Earth's surface, ocean plastic pollution is obviously a global problem. And if actions aren't done soon, this problem would only get worse.

Main image from Shutterstock; for illustrative purposes only.

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