Cold incoming water can be pre-warmed by passing it around warm wastewater from the shower.

Recovering about 60% of the energy invested.

^{Click the image for a DIY approach}

Heating enough water to meet the showering requirements of a modern household consumes a significant amount of energy - regardless of whether the fuel of choice is electricity, gas or oil - and this is set to rise.

According to the Energy Savings Trust, as homes become more energy efficient, heating water will account for up to 70 per cent of household energy bills.