Fire Standpipes are rigid water piping built into multi-story buildings to which fire hoses are connected. Standpipes serve the same purpose as fire hydrants. Dry standpipes extend into a building and are used by firefighters to supply water to the interior of the structure. Dry standpipes are not normally filled with water; when a fire occurs water is introduced into them. They can be used only by firefighters. Wet standpipes are filled with water and pressurized at all times and can be used by building occupants, generally with attached hoses.