Paris inaugurates giant water storage basin to clean up the River Seine for Olympic swimming

French officials have inaugurated a huge storage basin meant to keep cleaner the River Seine, which is to be the venue for marathon swimming at the Paris Games and the swimming leg of the Olympic and Paralympic triathlons.

The giant hole can hold the equivalent of 20 Olympic swimming pools of dirty water that will now be treated rather than being spat raw through storm drains into the river.