The present groundwater isoline map describes the groundwater situation of the main aquifer by means of the violet coloured groundwater isolines and the blue coloured of the Panke Valley aquifer in the North East of Berlin. These show the piezometric surface area of the unconfined and confined groundwater (see also Fig. 3). In areas of the main aquifer with confined groundwater the groundwater isolines are displayed in broken lines. In areas with no main groundwater aquifer or with an isolated main groundwater aquifer of low thickness no groundwater isolines are displayed. Those areas are defined with dots.
The map basis is the topographical General Map of Berlin, 1:50,000, in grid format, and the new geological outline for the Berlin state area, that was derived from the geological General Map of Berlin and surrounding, 1:100,000. In addition, the appropriate supporting points (groundwater measuring points, surface water levels) as well as the individual waterworks are indicated, with their wells and water conservation areas.
On the plateaus, the main aquifer is extensively covered by the glacial till and bolder clay (aquitards) of the ground moraines. Wherever the piezometric surface of the main aquifer lies within this aquitard, groundwater conditions are confined. This may at times result in the formation of floating groundwater in sandy areas above the glacial till . It may ascend to the surface after extreme precipitation. The ground-water levels of these high differentiated areas are not detected. Inside the the glacial till sandy segments can be filled with groundwater, the so called perched groundwater (see also Fig. 3).
On the Barnim Plateau to the north, an independent coherent bigger aquifer has developed in the Panke Valley. It is located over the main aquifer, which is covered by the glacial till of the ground moraine (see also fig. 7). In the present map, this aquifer is indicated by own groundwater isolines (blue). A spur of the glacial till toward the Warsaw-Berlin Glacial Spillway creates an interlock of the Panke Valley aquifer with the main aquifer there.
As a rule, the groundwater incline such as the floating direction in Berlin is oriented from the Barnim and Teltow Plateaus and the Nauen Plate toward the receiving bodies, the Spree and Havel Rivers.
Depression cones have formed around the wells at the waterworks; during the measurement period, they have sunk the groundwater surface below the level of the neighboring surface waters: Thus, in addition to inflowing groundwater from the shore side, the water pumped here also includes groundwater formed by infiltration (bank-filtered water) from these aboveground waters (see also Fig. 4).
However, in May 2006, the phreatic surface, which has been lowered in Berlin by drinking-water discharge over the past hundred years, was, all in all, compared to 1989 at a relatively high level, as it had been during the previous nine years. The reason for this is the reduced raw-water discharge by the Berlin Water Utility as a result of the falling needs of drinking and industrial water. Five smaller Berlin waterworks (Altglienicke, Friedrichsfelde, Köpenick, Riemeisterfenn und Buch) discontinued their production altogether during the period between 1991 and 1997 were closed during the period between 1991 and 1997: Altglienicke, Friedrichsfelde, Köpenick, Riemeisterfenn and Buch. In addition, drinking water production at the two waterworks Johannisthal and Jungfernheide was discontinued temporarily since September 2001; at the latter, the same was true for artificial groundwater recharging. In the context of immediate measures of water management by the Senate Department for Urban Development, groundwater is, however still discharged at the location Johannisthal, so as not to endanger current local waste disposal and construction measures. Likewise at the location Jungfernheide groundwater has been discharged by the Senate Department for Urban Development until the end of 2005. Since January 2006 a private concern continues this work.
The overall discharge of the waterworks for drinking water purposes has dropped by over 44 % in Berlin during the past 17 years (Fig. 9). In 1989, 378 million m3 were discharged, as opposed to 219 million m3 in 2002. In 2003 the discharge increased lightly to 226 million m3 because of the dry summer, to fall again in 2005 to 212 million m3.