Water pollution in the Philippines is a growing problem due to rapid urbanization and
industrialization. One major cause of water pollution is untreated domestic wastewater, which
accounts for 48% of total BOD pollution nation-wide (2237 thousand metric tons per year).
Metro Manila (MM), home to some 12 million people (14%), is an important economic zone,
producing 35.7% of GDP in 2003. All Manila waterways are heavily polluted and the situation is
grave as described below – MM’s key urban watercourses, Marikina River and Pasig River, are
biologically dead. About 65-75% of pollution is caused by residential sewage, with the rest
originating from industries such as tanneries and textile mills, as well as from solid waste
dumped in the rivers.