Drainage, Waste & VentQuestion 165 of 360
In a horizontal wet-vent system, how must the wet-vented pipe (which carries both waste and air) be sized?
a.Per the DFU load of the wet-vented section, and at least 2 inches where a water closet drains through it
b.at 1-1/4 inch minimum only
c.the same as the smallest fixture drain
d.at 4 inches regardless of load
Explanation
The wet-vented pipe must be sized for the drainage fixture unit (DFU) load of the fixtures it serves, and must be at least 2 inches where a water closet discharges into it. Adequate size keeps the pipe partially full so air can pass above the waste to vent the group. Undersizing would let the pipe flow full and lose its venting action.
Law Reference: 2022 California Plumbing Code (CPC) §908.0Practice all 360 questions free — no signup required.
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