The Halimun Massif is a vital watershed, being the source of several important rivers supplying both the urban and farming communities of West Java. To the north large rivers flow towards the densely populated regencies of Tangerang and Bogor, while to the South Sukabumi and Lebak regencies and the coast are fed by many small rivers. The park's forested ridges slowly release water helping to preventing floods in the wet season and water shortages in the dry season.