The Wurm is a left (western) tributary of the River Rur (Roer River). The Rur becomes a tributary of the Meuse River.
The sources of the Wurm are several brooks in the forests southwest of Aachen, which form the Wurm after the Diepenbenden reservoir. From there the Wurm nowadays flows through canals through the city of Aachen, until it resurfaces at the Europaplatz in the east of Aachen. North of Aachen (between Kerkrade and Herzogenrath) the river forms the border with the Netherlands for approx. 10 km. It flows into the River Rur near Heinsberg.