A 50,000 cubic metre rainwater storage basin is being built behind the Gare d'Austerlitz in Paris to reduce the amount of sewage discharged into the Seine during rainy periods. The project is due to be completed before the Olympic Games in the summer of 2024. By limiting discharge of polluted water into the Seine, the authorities hope to improve water quality and make the river swimmable for all by 2025. IMAGES AND SOUNDBITES