Drainage, Waste & VentQuestion 63 of 360
Each fixture trap must have a water seal with a depth of not less than and not more than:
a.1 to 2 inches
b.1-1/2 to 3 inches
c.2 to 4 inches
d.3 to 5 inches
Explanation
The CPC requires each trap to have a liquid seal of not less than 2 inches and not more than 4 inches, except for special deep-seal traps. A shallower seal is easily lost to evaporation or siphonage, and a deeper seal beyond code is only allowed for approved deep-seal designs. The other ranges fall outside the required 2 to 4 inch window.
Law Reference: 2022 California Plumbing Code (CPC) §1002.0Practice all 360 questions free — no signup required.
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