Drainage, Waste & VentQuestion 147 of 360
A vent must rise vertically to at least what point before it may offset horizontally, to keep waste water out of the dry vent?
a.2 inches above the trap weir
b.the center line of the drain
c.at least 6 inches (152 mm) above the flood-level rim of the fixture served
d.12 inches above the floor
Explanation
A vent must rise vertically to at least 6 inches above the flood-level rim of the fixture it serves before it may run horizontally. Below that height the pipe could carry or hold waste water, which would obstruct the vent. Keeping the horizontal offset above the flood-level rim keeps the dry vent dry.
Law Reference: 2022 California Plumbing Code (CPC) §905.0Practice all 360 questions free — no signup required.
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