This is the ingenious creation of Ravensbourne College’s Ines Sanchez Calatrava.

Draining waste water from the basin directly into the toilet’s cistern not only saves water but space, with no need for bulky tanks or pumps within bathroom walls. She hopes it will catch on in the developing world where water is scarce, as well as in bathrooms, commercial spaces and even summer festivals in the UK. “My ideal is that an overseas aid organisation would be interested in taking the idea forward,” she said.