What is the consequence if the above-ground portion of a building drain discharges into a vertical pipe according to the rules?

• A. It must connect to the building sewer.
• B. It must connect to the storm sewer.
• C. It must discharge to the ground.
• D. It must be redirected to the rooftop drain.

Answer: (A)

Sanitary waste must flow to the building sewer, not into a vertical vent/stack. A vertical pipe is designed to vent and equalize pressure, not to receive sewage. If the above-ground portion of a building drain discharged into that vertical pipe, it could create odors, siphon traps, and cross-connection problems, plus it would violate how sanitary drainage is supposed to be routed. Therefore, the above-ground portion must connect to the building sewer so the waste is carried away properly to the municipal sewer or septic system. The other paths shown (stormwater or ground discharge) are intended for different drainage flows and are not appropriate for sanitary waste.