Drainage Lines

Drainage lines Stacks are vertical lines of pipe that extend from the horizontal building drain under the slab or in the basement up to and through the roof of the building. Although the general direction which these pipes run is vertical, they may be offset or run in a horizontal position on upper floors and still be identified as a vertical stack. In the industry these pipes are either known as soil stacks, waste stacks, or vent stacks depending on the purposes which they serve.
The distinguishing factor that gives soil stacks their name is that they receive discharge from water closets and urinals. Clean water fixtures such as sinks and showers may also tie into soil stacks.
Waste stacks are tied into clean-water fixtures only – such as sinks, showers, bathtubs, lavatories, and the like. Waste stacks never receive waste from fixtures such as water closets or urinals. If a fixture such as a water closet or urinal was ever tied into a waste stack, it would thereupon become a soil stack.