The Water Research Centre has collated, over a number of years, quantitative end-use (micro-component) water consumption information for over 700 properties in England and Wales. For a sample of this size, this is the most detailed set of data in the UK, and was used to inform some of the mandatory and voluntary standards that are in place in the UK today.
One such standard is in the new edition of Part G of the Building Regulations, published in 2010, which includes a water efficiency requirement for the first time. This is a whole-of-house water use standard set at a maximum of 125 litres per person per day. The voluntary Code for Sustainable Homes (the Code) also has a series of standards for water use in new homes varying from 90 to 120 litres per person per day. Both of these standards allow flexibility for people to choose what is installed in a new home (including new emerging technologies) provided they can achieve the specified water use figure. Whilst the Code is purely a design standard, the Building Regulation is a mandatory requirement and homes built to the building regulations should be inspected post-installation to confirm the devices installed have specifications in-line with the design standard.
To help inform the UK Government on the success of the approach, and to aid UK water companies develop 25 year projections of demand as part of their water resources planning, research assessing the real consumption of homes designed to these water efficiency standards has been carried out. Meter readings from a sample of homes were analysed alongside property information to identify actual water use and trends amongst property cohorts.
Results from our statistical analysis show that occupancy is the single most significant factor influencing per capita consumption and whether a home meets a given water efficiency design standard.