Water covers about 70% of the earth's surface but only 1% of that water is clean and suitable for drinking. That is why water is so important. However, because in most countries clean water can be accessed very easily, people usually take it for granted and have little or no concern for its availability. An average person in the United Kingdom uses about 150 litres of water per day and the demand keeps on rising by 1% every year since 1930. In a typical UK household the average use of water is 275 litres of which two thirds are used in the bathroom, either for flushing the toilet or for baths/showers (Save The Rain). Moreover, it is estimated that an office demands about 62 litres of water per head of which, around 63% is intended for uses such as toilet flushing. According to an article by Guardian, the consumption of water per UK citizen increases when "hidden factors are included" (meaning the production of food and clothing) to 4,645 litres (Felicity, 2008). The above, along with the fact that UK has less available water per person compared to most other European countries, means the situation is very bad for the UK and explains why communities and governments are concerned with water efficiency. Additionally, during 2007-2008, about 3 billion litres of water per day were wasted (figure includes Wales) due to leakages. This accounts for one fifth of the total distribution. However, the percentage has fallen by 35% since 1990-1994 and 1999-2000 but it has remained constant since then. In addition, in 2008 there were 723 serious pollution incidents that affected water, as well as land and air. About 10% of these incidents were caused by the sewage and water industries. (DEFRA, 2009) It can be seen that most of the clean/drinkable water used, is for purposes where grey-water and/or rainwater can be used and also, a percentage is lost due to leakages. This is why water efficiency is a key priority for communities and local governments.

The built environment plays a key role to water efficiency. As areas get more urbanised, the water demand increases, especially during hot periods when water is limited. This, over the time has led to the creation of an artificial water cycle which affects the local drainage pattern and other hydrological features. It also increases the need to get water from other resources. According to the same article by Guardian, "The UK has become the sixth largest net importer of water in the world [...] Only 38% of the UK's total water use comes from its own resources; the rest depends on the water systems of other countries, some of which are already facing serious shortages" (Felicity, 2008). This has also an indirect impact on the environment since treating and distributing water requires energy resources which emit carbon dioxide. Moreover, one of the most crucial effects of the built environment in the water cycle is the prevention of natural soak away and the runoff of water, which increases the risk for flooding. A study contacted by Samuel D. Brody et al to identify the impact of the built environment on flood damage in Texas, USA concluded that damages caused by floods is not only because of the rainfall but also because of human development (Brody, Zahran, Highfield, Grover, & Vedlitz, 2007). Hence, in order to improve water efficiency, water management is mandatory.

A way of successfully managing water is to adopt environmental assessment methods. These can be distinguished into two categories: the mandatory and the voluntary. The Building Regulations, which were made a legal requirement by the Building Act in 1984, are a compulsory method. They are formed to ensure the health, safety, welfare and convenience of people in and around buildings and apply to most new and many existing buildings. However they only cover basic performance standards and not the quality of construction. Water efficiency is part of the Approved Document Part G. In the 2009 revised version it is stated that