For commercial buildings there are four main types of water that need to be considered, these are potable water, greywater, blackwater and stormwater. Potable water is generally defined as 'water which is suitable for human consumption' (Australian Standards, 2003) and is commonly referred to as drinking water. Greywater is the domestic wastewater from bathroom fixtures (such as basins, showers and baths), laundry fixtures (such as clothes washing machines and laundry troughs) and kitchen facilities (such as sinks and dishwashing machines). Depending on the level of wastewater treatment, greywater can be recovered and used for applications such as toilet flushing and irrigation. Blackwater refers to 'waste discharges from the human body' (Australian Standards, 2000), which are collected through fixtures such as toilets, urinals and bidets. It is possible to use this wastewater for non-drinking purposes once treated and disinfected. Stormwater refers to run-off due to rainfall collected from roofs, impervious surfaces and drainage systems (Australian Standards, 2003). Stormwater collected from roofs (also referred to as rainwater) can be used untreated for applications such as wash-down, irrigation and toilet flushing.
The industrial/commercial sector uses around 21% to 30% of the total potable water use in Australian urban centres. Within the sector the largest users of potable water are main retail shops, educational uses, professional offices, and hotels/taverns. Educational facilities are likely to include water use for irrigation of sports ovals and grounds.
Where water is used within a building depends on the building type. For example, the majority of water used in a restaurant is for kitchen applications, whereas for other buildings, such as office buildings, kindergartens and large shopping centres, the majority of water is used in cooling towers. Reducing water consumption in buildings and improving water efficiency is a major aspect of creating sustainable commercial buildings.
The benefits of implementing water efficiency initiatives in buildings may include:
* cost savings in annual water bills, particularly when the price of water is likely to increase, based on the current drought conditions
* adding to the corporate image of a business/organisation
* reduced energy costs and greenhouse emissions
* helping to ensure water is available for future generations.