Water Saving Regulations

As of 6th April 2010, new building regulations came into place that for the first time ever will address water efficiency.

Amendments to the legalisation state:

• Requires that for any new dwelling the potential wholesome water consumption by persons occupying it must not exceed 125 litres per person per day. The potential consumption must be calculated in accordance with the methodology set out in The Water Efficiency Calculator for New Dwellings

The average UK use is 150 litres per person, per day; this does vary from region to region but overall this would equate to an approximate 18% reduction in water consumption.

Also in 2010 a new water efficiency calculator for new dwellings was produced to ensure that fittings and appliances used during construction are as efficient as possible. This now supersedes the upgraded calculator that was originally released in 2009. Fittings and appliances should initially be specified during the design stage; the water efficiency calculator should be completed during this stage and then revised if those fittings subsequently change throughout the course of the build.

There are various assumptions that the water efficiency calculator uses in order to measure compliance. These include:

• That a person spends 5.6 minutes in the shower
• The average person flushes the toilet 4.42 times a day
• When running a bath, it is filled halfway up before getting in (50% of maximum volume)
• If there is a bath and a shower in the dwelling the shower is used 80% of the time and the bath 20% of the time
• a default figure is used of 17.16 litres per person for a washing machine and 4.5 litres per person for a dishwasher

The Building Regulations 2010 – Sanitation, hot water safety and water efficiency – approved document G, also states:

• Reasonable provision must be made by the installation of fittings and fixed appliances that use water efficiently for the prevention of undue consumption of water.
• a record of the sanitary appliances and white goods used in the water consumption calculation and installed in the dwelling is provided along with sufficient other information enabling building owners or occupiers to maintain the building and its services so as to maintain the water efficiency of the building. In this context, relevant white goods are washing machines and dishwashers

Rainwater and Greywater

Interestingly the amended regulations also take into account both rainwater and greywater as an alternative to wholesome water in certain situations. Wholesome water is still required to be utilised to supply showers, baths, bidets washbasins, sinks (in an area where food is prepared), and any place where drinking water is to be sourced. Providing an appropriate risk assessment has been carried out rainwater and greywater can be used for WC and urinal flushing, washing machines and irrigation. Alternatives to wholesome water are listed as water from wells, springs, boreholes or water courses; harvested rainwater; reclaimed greywater; and reclaimed industrial process water.