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.
MM is located in the hydraulically complex Pasig River – Laguna Lake – Manila Bay watershed,
which includes more than thirty tributaries within the urban area. Manila Bay is a pollution
hotspot in the East Asia Seas region (Map 1). Laguna Lake, located in the south of Metro
Manila, receives significant water pollution from MM region. Paradoxically, it is also a crucial
raw water source for the MM region. The Pasig River provides an important two-way hydraulic
connection between Manila Bay and Laguna Lake, and because of this interconnection, the Pasig
River serves as a conduit to transfer pollutants and salinity between Manila Bay, the Laguna
Lake, and other urban watercourses.