A dry riser is normally an empty pipe that can be externally connected to a pressurised water source by firefighters. It is a vertical pipe intended to distribute water to multiple levels of a building or structure as a component of the fire suppression systems.
Most buildings have a "wet riser" or "wet standpipe" system where the pipes are kept full of water for manual or automatic fire fighting operations. Dry risers are used when the water pressure of a building wouldn't be enough for fire suppression and in unheated buildings where the pipes could freeze.
Dry risers must allow fire engine access within 18 m of the dry riser inlet box. For occupied buildings, it must be within a fire-resistant shaft, usually one of a building's fire escape staircase enclosures. It can also be installed where the gauges, valves, and alarm devices are located.