This introduces a minimum water efficiency standard into the Building Regulations for the first time for new homes. It requires that the average water usage of a new home (including those created by a change of use) is no more than 125 litres per person per day or 110 litres/person/day if required as part of the planning permission Estimated water usage must be calculated in accordance with the methodology set out in Appendix A of Approved Document G, unless 'deemed to satisfy' fittings described in Approved Document G are used.