Taking a shower is better for the environment, and your pocket, than having a bath which uses 80 to 100 litres of water. But a modern power shower can use 20 litres of water a minute, easily putting out 100 litres in 5 minutes.Different showers mean water use varies from house to house, so whilst timing your shower is a step in the right direction, that won't tell you how much water you're using.