Five-hundred litres (132 gallons) of water per second are jetted to an altitude of 140 metres (459 feet) by two 500kW pumps, operating at 2,400V, consuming over one megawatt of electricity.The water leaves the nozzle at a speed of 200 km/h (124 mph). When it is in operation, at any given moment there are about 7,000 litres (1849 gallons) of water in the air. Unsuspecting visitors to the fountain--which can be reached via a stone jetty from the left bank of the Lake--may be surprised to find themselves drenched after a slight change in wind direction.
The first Jet d'Eau was installed in 1886 at the Usine de la Coulouvrenière, a little bit further downstream from its present location. It was used as a safety valve for a hydro power generator and could reach a height of about 30 metres (98 feet). In 1891, its aesthetic value was recognised and it was moved to its present location to celebrate the Federal Gymnastics Festival and the 600th anniversary of the Swiss Confederation, on which occasion it was illuminated for the first time. Its maximum height was about 90 metres (295 feet). The present Jet d'Eau was installed in 1951 in a partially submerged pumping station to pump lake water instead of city water.
Since 2003, the fountain has operated during the day all year round, except in case of frost and particularly strong wind. It also operates in the evening between spring and autumn and is lit by a set of 12 lights totaling 108kW.