Deep infiltration is an important component in the water cycle. It refers to the water that leaves the soil area accessible to plants downwards and after some time joins the groundwater as so-called groundwater recharge. How large this amount is depends, among other things, on the weather, the soil and the vegetation. A change in these factors also changes the deep seepage. For many years, deep infiltration can be viewed as precipitation water that is not released into the atmosphere through interception and soil evaporation as well as root uptake and transpiration from vegetation. In order to investigate the influence of different tree species on deep seepage, nine large lysimeters were set up on the “Britz” forestry test area near Eberswalde and planted with pine, Douglas fir, beech and larch trees in 1974. Between 1999 and 2000, two pine stands were underplanted with beech and oak. A larch site was underplanted with beech and a larch site was converted into a young oak stand. Assuming that we have the same soils and climate here, differences in the measured deep infiltration indicate the influence of the different vegetation on the lysimeter.