Branch (lateral) lines are defined as piping sections that serve which of the following?

• A. A single room
• B. A room or group of rooms on the same story
• C. Outdoor distribution
• D. The building's main trunk

Answer: (B)

Branch lines are the piping segments that distribute water to fixtures within a localized area. They typically serve a room or a group of rooms on the same story, branching off from the main trunk or riser and running horizontally to reach those fixtures. This distinguishes them from the building’s main trunk, which carries flow toward multiple branches, and from outdoor distribution, which serves exterior areas. So the defining role of a branch line is to supply a defined zone—usually one room or a cluster of rooms on the same floor.