Drainage, Waste & VentQuestion 109 of 360
Loss of a trap seal from siphonage or back pressure is primarily prevented by:
a.Proper venting of the drainage system
b.Using a larger trap
c.A deeper seal alone
d.Adding a cleanout
Explanation
Venting introduces air to equalize pressure in the drainage system, which prevents siphonage and back pressure from pulling or pushing out the trap seal. A larger trap or a deeper seal alone does not correct the pressure imbalance, and a cleanout serves maintenance, not seal protection.
Law Reference: 2022 California Plumbing Code (CPC) §901.0Practice all 360 questions free — no signup required.
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