Nature Reengineered: the Self-Cleaning Swimming Pool

"Of Soil and Water" art installation at King's Cross Railway Station, London, that created a 'natural' chemical free outdoor swimming pond with biological water purification. As the installation notes state:

'a natural, closed-loop [water purification] process using wetland and submerged water plants to filter the water and keep it clear. The number of bathers was restricted by the amount of water the system was able to clean. Thus, the use of the pond remains in balance with what nature can absorb and regenerate.'