The Woluwe is a stream that goes through several municipalities in the southeast and east of Brussels and is a right tributary of the Senne/Zenne (in Vilvoorde). The Kleine Maalbeek is a tributary of the Woluwe (in Kraainem). Many ponds formed along the stream over time, among which the Mellaerts Ponds still exist. The valley of the Woluwe crosses the municipalities of Auderghem/Oudergem, Watermael-Boitsfort/Watermaal-Bosvoorde, Woluwe-Saint-Pierre/Sint-Pieters-Woluwe, Woluwe-Saint-Lambert/Sint-Lambrechts-Woluwe, Evere, Kraainem, Zaventem, Diegem and Vilvoorde.
The towns of Woluwe-Saint-Pierre/Sint-Pieters-Woluwe, Woluwe-Saint-Lambert/Sint-Lambrechts-Woluwe and Woluwe-Saint-Etienne/Sint-Stevens-Woluwe derive their name from it.