Revision of Berlin / Water from Wed, 05/11/2011 - 11:01

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Description of the problem

Berlin has an area of 880 km² and a population of 3.4 million. The largest distance from east to west is 45 km, from north to south 38 km.

In east-west direction, the Spree flows through the city forming a roughly 7 km wide valley – bordered in the north and south by plateaus – that terminates in the valley of the Havel at Spandau. These valleys form part of the Berlin-Warsaw ancient river valley that provides the treasured groundwater under the city.But in terms of feeder streams and precipitation, the metropolitan area of Berlin suffers from a water shortage. The lakes are shallow, the rivers are slow-running and, especially in summer, carry little water. This makes Berlin's bodies of water ecologically very sensitive systems. The water supply and wastewater disposal for the city of Berlin depends in large measure on influents from the brown coal open-cast mining areas of Brandenburg. The quantity of groundwater being pumped there into the Spree River is decreasing because of the decline in brown coal extraction, and it will decrease further.

For the purpose of regulating the rate of flow of the Spree, large reservoirs are planned or are already under construction. High levels of direct and indirect discharge from sewage works, use of the river for industrial and other purposes, the effects of shipping and leisure seekers are all impairing the water quality. On account of the high level of sealing of the city, when it rains, large amounts of polluted storm water flow through the separate drainage system into the water bodies.

The main water quality problems are eutrophication, the associated growth of algae, and damage to the oxygen balance caused by eight major sewage plants. Following technological improvements, phosphate and nitrogen effluents from the sewage works, and thus pollution, have been reduced substantially since the end of the eighties. In order to obtain the clean-up goal of water quality Class II – slightly eutrophic – further upgrading of the sewage works and storm water drainage measures are necessary and planned. Unlike many other cities, drinking water is obtained in Berlin solely from groundwater extracted within the city. Drinking water wells are mostly in the immediate vicinity of the water bodies. Thus, two-thirds of the water extracted actually consist of bank filtrate or artificially recharged surface water. Therefore, the quality of both the surface and groundwater is very important for the drinking water supply. It is estimated that about 40% of groundwater reserves are threatened by contamination, mainly by some 5.500 old polluted sites and areas not yet connected to the sewage system. The main problems are heavy metals, phenoles, hydrocarbons, and ammonium. Unlike in many federal Länder, nitrate pollution is not a problem. While cleaning up the polluted sites will take a long time yet, the sewage system is scheduled to be completed by the end of the nineties. Ever more sealing of the city and rising water consumption had caused the groundwater table to sink sharply until the beginning of the eighties. Since then, the water table has risen significantly thanks to a 25 % decline of in water consumption and more widespread groundwater replenishment. The regulations and instruments for the management and protection of surface and groundwater resources are based on federal laws governing water resource management and wast water disposal and passed at the end of the eighties, and on the 1989 Berlin Water Act. In the meantime, attempts are being made, with increasing success, to influence the use and consumption of water resources using economic instruments, such as fees and prices. The shortage of surface and groundwater resources in Berlin and their vulnerability mean that there is a special need for sustainable water resource management. This must apply both to the quantity and quality of the water. In the future, water must be used only in such a way that it becomes available again, in a short cycle, for drinking and industrial purposes. In terms of water use, sustainability means: extraction of the water within the confines of the city minimising the quantity of water used; groundwater withdrawal must be proportional to replenishment and recharge; there is a direct correlation between drinking water use and surface water quality; this requires particular efforts with respect to pollution control of the water bodies; consequently, the standard of wastewater treatment must be particularly high; treated wastewater must be used to boost the rate of flow of the bodies of water; a high degree of storm water retention in the area.

Drinking water

All the drinking water for Berlin - 100 % of some 205 million cu.m. in 2008 - is obtained from groundwater. Moreover, the groundwater resources were tapped by private and industrial water users, as well as for large-scale groundwater retention measures for construction projects, groundwater redevelopment measures and heat use. The Spandau, Tegel, Tiefwerder, Beelitzhof, Kladow, Wuhlheide, Kaulsdorf and Friedrichshagen waterworks, which are currently used to supply Berlin's drinking water, are located in the Warsaw-Berlin Glacial Spillway or the Havel Channel .Only the Stolpe waterworks north of Berlin takes its water from the State of Brandenburg, and sends to the city water amounting to a maximum of 9 % of the total discharge of the BWB for the public water supply of Berlin. It is maintained by the BWB, and is also responsible for providing drinking water to several nearby Brandenburg communities.