To which side of the trap must the overflow pipe connect?

To which side of the trap must the overflow pipe connect?

• A. Inlet Side of the fixture trap
• B. Outlet Side of the fixture trap
• C. Top of the trap
• D. Bottom of the trap

Answer: (A)

The overflow should be connected to the drain on the inlet side of the fixture trap. This places the trap between the overflow water and the rest of the drainage system, preserving the water seal that blocks sewer gases and ensuring any overflow water travels through the trap before exiting to the building drain. If the connection were on the outlet side, the overflow could bypass the trap or disturb the trap’s seal, increasing the risk of odors or backflow. The connection needs to attach at the inlet path so the fixture’s drainage and overflow share the same trap-controlled path.

The overflow should be connected to the drain on the inlet side of the fixture trap. This places the trap between the overflow water and the rest of the drainage system, preserving the water seal that blocks sewer gases and ensuring any overflow water travels through the trap before exiting to the building drain. If the connection were on the outlet side, the overflow could bypass the trap or disturb the trap’s seal, increasing the risk of odors or backflow. The connection needs to attach at the inlet path so the fixture’s drainage and overflow share the same trap-controlled path.