What is a Leader in plumbing terminology?

In plumbing terminology, a leader refers to a vertical exterior storm piping system that conveys rainwater or stormwater from the roof or other surfaces to a designated drainage system. Leaders are often associated with downspouts, which are vertical pipes that direct rainwater collected from gutters down to the ground or into a drainage system. This is crucial for preventing water accumulation around the foundation of a structure, which can lead to flooding or structural damage.

The other options do not accurately describe a leader. While horizontal piping for wastewater is an important component of plumbing systems, it does not fit the definition of a leader, which must be vertical and associated with stormwater. An underground sewer pipe conveys waste, and while it is essential to plumbing, it serves a different function than a leader. Lastly, while measurements of pipe length are important in plumbing for ensuring correct fittings and installation, they do not pertain to the term leader itself.