<P> The wall - mounted type is connected to the building's water supply for a continuous supply of water and electricity to run a refrigeration unit to cool the incoming water, and to the building's waste disposal system to dispose of unused water . Wall - mounted water coolers are frequently used in commercial buildings like hospitals, schools, businesses, and other facilities . </P> <P> In the standard wall - mounted cooler, also commonly referred to as a water fountain or drinking fountain, a small tank in the machine holds chilled water so the user does not have to wait for chilled water . Water is delivered by turning or pressing a button on a spring - loaded valve located on the top of the unit, that turns off the water when released . Some devices also offer a large button on the front or side . Newer machines may not have a button at all; instead, a sensor that detects when someone is near and activates the water . Water is delivered in a stream that arches up, allowing the user to drink directly from the top of the stream of water . These devices usually dispense water directly from the municipal water supply, without treatment or filtering . </P> <P> Wall mount water coolers come in a wide variety of styles, from recessed models to splash resistant, contoured basins protruding out from the wall, traditional rounded square edge designs, bottle filler and water cooler combination units, bi-level designs, and other features and options . </P> <P> Water dispensers commonly have the water supply vessel mounted at the top of the unit . Bottom - load water dispensers have the vessel mounted at the bottom of the unit to make loading easier . </P>

Why are there two taps on a water cooler