The people of Riehen, a small city near Basel in Switzerland, have long wanted a new public swimming pool to replace their “obsolescent baths” by the River Wiese. In the late 1970s, the city government even launched a design competition. Unfortunately, the initial vision was never unrealized, but, just a few years ago, the Swiss architecture firm Herzog & de Meuron got to thinking about new possibilities. They write: “the changed perspectives brought by the intervening years prompted the idea of abandoning the conventional pool concept, with its mechanical and chemical water treatment systems, in favor of a pool closer to a natural condition with biological filtration.” The citizens liked the idea, giving it the thumbs-up in a municipal vote.
Herzog & de Meuron say their new approach enables “technical systems and machine rooms to vanish.” Their all-natural approach means no chlorine or other chemicals are added; filtering plants help keep the water clean.
Biological water treatment basins, which are the “heart of the baths,” also play a major role. DesignBoom tells us: “The process is modeled after natural, terrestrial water purification, through layers of gravel, sand, and soil.” Herzog & de Meuron worked with Swiss landscape architecture firm Fahri und Breitenfeld on the system.
Amazingly, this all-natural approach enables the bath to accommodate up to 2,000 people a day, who enter as they would a small pond. DesignBoom writes: “Its edge takes an irregular and vegetated boundary, with various methods for guests to enter the water. These include a gently sloping gravel beach, staircases, as well as wood docks that allow for a jump.”
The structures around the natural pool are modeled on the local “Badi,” or Basel’s “traditional wooden Rhine-side baths.” Timber walls provide screen on the north and west sides, with built-in recliners for sunbathing.
There are also open-air showers and a small cafe.