The exact knowledge of the current ground-water levels, and hence also of groundwater stocks, is imperative for the State of Berlin, since 100% of the drinking-water supply (approx. 220 million m³ in 2001) is obtained from groundwater. This groundwater is pumped at nine waterworks, almost entirely from the city’s own area. Only the Stolpe Waterworks on the northern outskirts obtain water from Brandenburg, but also supply Berlin.
Moreover, groundwater reserves are tapped for in-house and industrial use, as well as for major construction projects and heating-related purposes. Numerous instances of soil and groundwater contamination are known in Berlin, which can only be rehabilitated on the basis of exact knowledge of groundwater conditions.
Definitions Regarding Groundwater
Groundwater is underground water (DIN 4049, Part 3, 1994) which coherently fills out the cavities in the lithosphere, the movement of which is caused exclusively by gravity. In Berlin, as in the entire North German Plain, the cavities are the pores between the rock particles in the loose sediments. Precipitation water which seeps (infiltrates) into the ground first of fills out these pores. Only that part of the infiltrating water which is not bound as adhesive water in the non-water-saturated soil, or used up by evaporation (evaporating transpiration), can seep to the phreatic surface and form groundwater (Fig. 1).