The Pasig River is a river in the Philippines that drains Laguna de Bay into Manila Bay. The river is called Ilog Pasig in Filipino. It stretches for 25 kilometers and divides Metro Manila into two. Its major tributaries are Marikina River and San Juan River.

The Pasig River used to be an important transport route in Spanish Manila. However, due to negligence and industrial development, the river has become very polluted and is considered dead (not able to sustain life) by ecologists.

The Pasig River Rehabilitation Commission(PRRC) was estalished to oversee rehabilitation efforts for the river. Supporting the PRRC are private sector organizations i.e. Clean and Green Foundation, Inc. who implemented the Piso Para sa Pasig campaign.