Drainage, Waste & VentQuestion 161 of 360
A combination waste-and-vent system is chiefly intended for…
a.floor drains, sinks, and similar fixtures where conventional venting is impractical, using oversized horizontal piping
b.a battery of water closets
c.roof (storm) drainage
d.water-heater relief piping
Explanation
A combination waste-and-vent system uses oversized horizontal drain piping that carries both waste and air, providing venting for fixtures like floor drains and sinks in large open areas where a conventional vent cannot be run. Water closets and other high-discharge fixtures are generally not permitted on this system. The oversized pipe flows only partially full so air can move above the waste.
Law Reference: 2022 California Plumbing Code (CPC) §910.0Practice all 360 questions free — no signup required.
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