Figures are from:

The £260 million/year figure includes £119.3m in water bills and £141m in energy bills to heat the water. This is based on the following calculation:

 

Substantiation Table 1.png

The £104.10/year figure includes £47.70 in water bills and £56.40 in energy bills to heat the water. This is based on the following calculation:

 

Substantiation Table 2 .png