In plumbing terminology, what is the vertical water supply pipe that carries water to main branches called?

• A. Riser
• B. Trunk Line
• C. Branch Line
• D. Supply Leg

Answer: (A)

The vertical pipe that carries water upward through a building to feed the distribution on multiple floors is called a riser. It runs vertically and typically connects to horizontal distribution on each floor, delivering water to the main branches that feed fixtures. This is why the term riser fits the description: it’s specifically about the vertical delivery path in a multi-story system. The other terms describe different parts of the network—trunk lines are large mains that feed sections (often horizontally), branch lines run from those mains to individual fixtures, and supply leg isn’t a standard term for this role.