MOST people drink about 2 litres of water a day, but consume 3,000 a day if the water that goes into their food is taken into account. Rich countries use more as their consumption of meat, which is far more water-intensive than grain, is higher. Around 1.2 billion people live in places that are short of water, and it is running out in others such as northern China and western America. Meanwhile, the world’s population is growing and more water will be needed to feed it. Farming, which accounts for some 70% of human water consumption, offers the best opportunity for thrift. Repairing leaks and better irrigation in poor countries could help reduce wastage by up to 70%, as could switching to less thirsty crops in arid regions.