The Tajuña gets its water from springs and from the Calizas del Páramo de la Alcarria aquifer which covers 1,800 km² at a depth of 30–40 m.
In terms of its water supply, the Tajuña River relies on both natural sources, such as springs, and the extensive Calizas del Páramo de la Alcarria aquifer that spans 1,800 km² at a depth of 30–40 m.