You’re in for a surprise. According to The Economist, it takes 140 litres! Or so my printed edition says. According to their numbers, 1120 litres goes into making one litre of coffee, which translates into cups of 0.125 litres; I’m afraid my cups are bigger than that. Anyway, water is scarce many places on earth. Maybe I should switch to tea, which only requires 15 litres per cup, or even better, water.