Standpipe

A standpipe is a vertical or near-vertical pipe assembly used to convey water or other fluids from a supply source to a designated endpoint. In buildings, standpipes are commonly part of the plumbing or fire protection system and may serve as risers that distribute water to various floors or zones.

In firefighting, standpipe systems provide a ready source of water for interior operations. They typically terminate at outlets on multiple floors where firefighters can connect hoses. Standpipe systems are classified by the type of outlet and access they provide: Class I outlets are designed for use by firefighters with 2.5-inch hoses and do not include a readily available handline; Class II outlets are equipped with a 1.5-inch handline for building occupants; Class III combines features of Classes I and II, providing both large-diameter outlets for firefighting and smaller handlines. Standpipes can be wet systems, where pipes are filled with water and pressurized at all times; or dry systems, where pipes are empty or pressurized only when water is introduced by a pump or riser system. Fire department connections (FDCs) enable external water supply to the standpipe.

Outside firefighting, standpipes appear in industrial and offshore settings as vertical pipelines that support process fluids, water distribution, or suppression systems. Design, installation, and maintenance follow applicable codes and standards to ensure reliability, accessibility, and safe operation. Regular testing, inspection, and compliance with standards (such as NFPA 14 in many regions) are required to verify performance and reduce risk.