In an architecturally important area of Berlin, situated between the Landwehr Canal, the Kulturforum (the Berliner Philharmonie and the Berlin State Library) and the new construction on Potsdamer Platz, a series of urban pools have been realised, with a combined area of approximately 1.2 hectares. The scale, the inner-city location and the integration of ecological, aesthetic and civil-engineering functions are unique.
The purpose of the water features in the highly urban context is explicitly twofold: design and ecology. The large water surfaces are fed entirely by rainwater. The water features improve the urban climate, since the water slightly lowers the ambient temperature in summer, binds dust particles and humidifies the air. The rainwater from the roofs of the surrounding buildings is captured in large underground cisterns. It is used for topping up the pools, for flushing toilets in offices and for irrigating green areas.
The water system, fed entirely by rainwater, is composed of a narrow channel in the north, water features near the Piazza, the large main water feature and another small water feature in the south.
The temporary retention in cisterns and pools is sufficient to guarantee that larger volumes of rainwater need only be discharged into the Landwehr Canal an average of three times every ten years. This is similar to an unpaved surface. The five cisterns have a total volume of 2,600 m3, of which 900 m3 is reserved for extreme rainfall. The main pool has an additional 15 cm buffering height, which translates as 1,300 m3. A great deal of attention is devoted to water quality, and in particular to clarity. Solid particles settle in the cisterns. From the cisterns the water is fed into the southern pool through seepage facilities. Once there, it runs directly through a biotope with vegetation, where it is treated. If necessary, filters can be added during summer months to filter suspended algae from the water. From the northern pool, too, water flows through a seepage facility, along treatment biotopes with vegetation and into the deepest point of the water features near the Piazza. The water is aerated as it passes through a series of multi-layered structures and set in motion near the Piazza.
The water features work without any chemical additives and consume little energy. The rainwater is buffered, less drinking water is used and a pleasant outdoor space has been created. Dreiseitl et al., 2006