The Bumbungan River is a river in the province of Laguna in the Philippines. It is commonly referred to as the Pagsanjan River because of the popularity of the municipality of Pagsanjan and Pagsanjan Falls, one of the province's tourist destinations. The municipality of Pagsanjan was named so because it is where the Balanac River, originating from Mount Banahaw, joins the Bumbungan. Its old name, Pinagsangahan, which literally means branching, was changed to Pagsanjan during the Spanish Colonial Era.

Laguna, officially the Province of Laguna, is a province in the Philippines located in the Calabarzon region in Luzon. Its capital is Santa Cruz while its largest city is the City of Calamba and the province is situated southeast of Metro Manila, south of the province of Rizal, west of Quezon, north of Batangas and east of Cavite. Laguna hugs the southern shores of Laguna de Bay, the largest lake in the country. As of the 2020 census, the province's total population is 3,382,193. It is the seventh richest province in the country in 2016.