Traps shall be self-scouring and shall not have interior partitions except where what is integral with the fixture?

• A. the fixture
• B. the vent system
• C. the drainage pipe
• D. the sewer line

Answer: (A)

Traps must be self-scouring to keep the interior clean as water drains, preventing solids from building up and blocking flow or letting sewer gases sneak through. Interior partitions inside a trap create dead zones where solids can collect and resist the moving water, which would defeat that cleansing action. The only time you can have an interior partition is if it’s built into the fixture itself—i.e., it is integral with the fixture. If the partition isn’t part of the fixture, it would trap debris and hinder cleaning, compromising the trap’s function. The vent system, drainage pipe, or sewer line aren’t relevant to this specific design rule.