It is a vertical pipe extending from a water supply, especially one connecting a temporary tap to the mains. Standpipe is filled with water and is pressurized at all times. In contrast to dry standpipes, which can be used only by firefighters, wet standpipes can be used by building occupants. Wet standpipes generally already come with hoses so that building occupants may fight fires quickly. This type of standpipe may also be installed horizontally on bridges.