In Unilever's London headquarters, Gavin Neath, the consumer goods group's head of sustainability, takes a plastic contraption out of its cardboard box and places it on a table. It looks like a small and semi-transparent version of the vending machines that dispense drinks to office workers.

The device is called a Pureit - and it is a drinks dispensing machine of sorts. Developed by Hindustan Unilever, the company's Indian subsidiary, the Pureit provides drinking water from any source, however polluted, purifying it with a series of meshes, parasite and pesticide traps and a germ-killing battery kit, without the need for boiling and without the use of mains electricity.