A dry riser is a type of standpipe used in a building or structure as a component of the fire suppression system, consisting of a vertical "riser" pipe with an external access point (usually at ground level, often at a Siamese connection) through which water can be pumped to sprinklers on individual floors, or to firefighters' hose attachments on each floor, in the event of fire. These pipes stand empty or "dry" until water is pumped into the external connection from a fire engine. The dry riser is related to a wet riser or wet standpipe system where the pipes are kept full of water for automatic operation.