A dry column is a normally empty pipe that can be connected externally by firefighters to a pressurized water source in the event of a fire. It is a vertical pipe used to distribute water to multiple floors of a building or structure as a component of fire suppression systems.

Most buildings have a "wet column" system, in which pipes are filled with water for manual or automatic firefighting operations. Dry columns are used when the building pressure will not be sufficient or in unheated buildings where water in pipes could freeze. In the United Kingdom, dry column intakes must be within 18 meters of a location that can be accessed by a fire truck.[1] Dry columns in inhabited buildings must run along fire-resistant corridors, usually one of the building's escape stairs. The patio is where the valves, meters and alarm devices are also located.

Depending on the terminology of each country, the term dry riser can refer to a vertical pipe that feeds hoses or a sprinkler system. A dry column has an external connection at street level to which a fire truck pump can be hooked to provide pressurized water on each floor. This external intake is sometimes called Siamese intake, since it is usually made up of a "Y"-shaped piece that allows the connection of two water supply hoses.

The term dry column is also sometimes used for sprinkler fire suppression systems that have their pipes filled with air (not water). When one of the sprinklers is activated (due to the presence of fire), the system is filled with pressurized water that was stored in a tank and is sprayed on the burned area.