Core TradesQuestion 140 of 700
A 3-inch-diameter horizontal drainage pipe should be installed at a MINIMUM slope of:
a.1/16 inch per foot
b.1/2 inch per foot
c.1/4 inch per foot
d.1/8 inch per foot
Explanation
Drainage pipes 3 inches in diameter and larger may be sloped at a minimum of 1/8 inch per foot, which keeps solids in suspension without draining the water too fast. Pipes 2-1/2 inches and smaller need a steeper 1/4 inch per foot. 1/16 inch per foot is too flat to self-scour.
Law Reference: 2025 CA Plumbing Code §708.0Practice all 700 questions free — no signup required.
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