The French city of Marseille is home to France's largest water treatment plant in an urban environment. 450,000 m3 of water is stored in a huge ten-metre-deep basin, the equivalent of 225 Olympic swimming pools. "This represents three days' production for this centre and around two days' supply for the whole of Greater Marseille", says Emmanuel Guiol, Deputy Director of Operations at the Société des Eaux de Marseille (SEM) (Marseille water company). IMAGES AND SOUNDBITES