To assist in reducing the amount of hot water required it is important when considering building design that the showers used are water saving showers.

These types of showers have an output of water considerably less than conventional showers without compromising on comfort.

The Ministry for the Environment introduced the Water Efficiency Labelling Scheme (WELs) in April 2010 which is to be phased in over 3 years and aims to educate the consumer on how to choose water efficient products.

Look for or specify products that have a WELs label as per this PDF.