The source is near the Schöpfl (893 m) in the Vienna Woods. The source streams are the Riesenbach, Lammeraubach, Agsbach, Hainbach and the Großkrottenbach which all confluence at Klausen-Leopoldsdorf forming the Schwechat. It flows through the small town Alland, through the Helenental to Baden and through the Vienna Basin to Schwechat, where the river ends in the Danube.