Currently in England and Wales all new dwellings require a Water Efficiency Calculation to ensure no person should use more than 125 litres and 110 litres respectively. In London no more than 105 litres is allowable.
Generally this calculation is only required at the ‘As Built’ Stage but it would be good practice to calculate before the purchase of any white goods or water fixtures or fitting to ensure no changes have to be made at completion stage to show compliance.
The above is also required to comply with building regulation document ‘G’.
Download Building Regulation document G, PDF
This document gives guidance for compliance with the Building Regulations for building work carried out in England. It also applies to building work carried out on excepted energy buildings in Wales as defined in the Welsh Ministers (Transfer of Functions) (No. 2) Order 2009.