This is a complicated... So here are some rules of thumb:-
This is a complicated picture given the number of methods to heat the water and the flows of water that various showering techniques provide.
- A medium sized bath uses 150L of water, a power shower for 10 minutes uses about 150L of water, so a bath and a power shower could cost about the same, if the water used in both is heated in the same way. A low flow shower uses about 50L of water and in this scenario, would cost about a third the price of a power shower.
- Many of us have a gas boiler and an electric shower. Electric showers are low flow and in ten minutes may use 50L of water, however electricity costs over 3 times as much as gas at the moment and so surprisingly enough a shower and a bath in this case cost about the same.