Herzog & de Meuron designed a biologically filtered swimming pool for the Naturbad Reihen in Switzerland. The Swiss architects responded to a desire from the local residents for an outdoor facility, opting for a more natural approach.
The bathing lake was designed to resemble the traditional wooden pools found along the Rhine river. Its cleanliness is maintained naturally, through water plants and layers of gravel, sand and soil. The absence of chemicals gives the impression that bathers are swimming in an actual lake, rather than a man-made pool.
The architects explain, "The standard geometric swimming pool transforms into a bathing lake where the technical systems and machine rooms vanish, to be substituted by planted filtering cascades."