The Umiray–Angat Transbasin Project (UATP) is an expansion project of the Metropolitan Waterworks and Sewerage System (MWSS) for the supply of the Angat Dam reservoir. The 13-kilometer-long (8.1 mi) 4.30-meter (14.1 ft) diameter tunnel-aqueduct system diverts waters from the Umiray River east of the Angat Basin. 20–30% of the water that is consumed in Metro Manila and its outlying regions is supplied by the Umiray Basin.