4. Water Requirement

A building in use may require water either related to the purpose of the building or for the user of the building. In addition, water is also required to keep the building usable. The use of water in a building may be for a single unique purpose or multiple purposes. To harvest rainwater in a building, it is of the utmost necessity to identify all of the purposes for the use of water and then to estimate the water requirement for those purposes. Water use in a building is mostly a continuous phenomenon throughout the day, and in some cases it is periodical or in few cases occasional. Considering the usual pattern and major purposes for water to be used in a building, the daily water requirement for the purposes of using water in a building should be determined. Water requirement for particular purposes varies depending on multiple factors such as behavioral, economical, social, cultural, environmental, and probable hazards. Therefore, the water requirement for a particular single purpose is not identical or unique for buildings of various occupancy types at various locations. Water requirement, and thus the demand for water for a particular purpose, varies from person to person, from time to time, and from place to place. As a result, the water requirement in a building for a particular purpose and occupancy type varies considerably for various locations. In this chapter, various water requirements for persons and thus for buildings are mostly identified and mentioned in tabular forms. In most cases, the water requirement or demand is furnished on a daily basis. In a few cases, the requirement is given in the context of particular considerations. The water requirement for some purposes, in particular areas on the globe, is also furnished.