A dry riser is a system of pipe work and valves that typically runs up through a building and is used by the fire brigade to allow them to transport water at pressure to where it is needed in the building (in some cases a dry riser system may run down through a building if it has multiple below ground floors i.e. an underground train station)

Essentially a dry riser is a solid hose with fireman’s connections allowing a fireman to connect his hose from a fire engine to the inlet while allowing another firefighter to connect a hose to a landing valve to where they can then fight the fire.