What Are Plumbing Riser Diagrams?
The New York City (NYC) Plumbing Code defines risers as water pipes that extend one full story or more and convey water to a group of fixtures (like baths, sinks, showers, and lavatories) or to branches that extend to fixtures on two or fewer consecutive floors. Branches do not include risers, mains water pipes, or stacks, the latter of which are vertical lines of soil (for sewage), waste (water from fixtures and appliances, commonly called gray water), vents (to get rid of harmful gases), or inside conductor piping (for storm water).
However, it isn’t only risers that are included in plumbing riser diagrams, as you can see in Design of Plumbing Systems below. For instance, the NYC Department of Building (DOB) requires stacks to be shown on plumbing riser diagrams even though they are not risers! So too does the NYC Plumbing Code.