In plumbing, what is a "waste arm"?

A waste arm refers specifically to the horizontal section of pipe that connects the fixture trap to the vertical stack or soil pipe. This component is essential for the proper drainage of wastewater from plumbing fixtures, ensuring that waste flows smoothly and efficiently into the drainage system. The waste arm plays a crucial role in maintaining the intended slope for gravity drainage, which prevents blockages and allows for effective waste removal.

The waste arm must be installed at the correct angle to facilitate drainage and must be adequately supported to prevent sagging or misalignment, which could lead to backup or leakage. By connecting the trap (which prevents sewer gases from entering the building) to the main drainage system, the waste arm helps ensure the overall functionality and hygiene of the plumbing system.