Good question! If you're trying to conserve water, taking a shower is one way to do so. Interestingly enough, it will depend on your shower head.
The average bath uses a total of 80 liters of water. However, if you take a long shower and you have a powerful shower head, you may be using more water than you would if you were taking a bath. The best thing to do is get an energy-saving shower head. It is even better to take a shower that takes about 10 minutes or less.