According to a study by Unilever an eight-minute shower uses 62 litres of hot water.

(People generally believe that taking a shower is more environmentally friendly than a bath, and this water consumption compares favourably against a bath, which uses an average of 80 litres, but if you use a power shower – an appliance that adds extra pressure to the water flow – then an eight-minute shower requires twice as much water and energy as a bath.  Maybe the answer is to share.)