Anti-Siphon P-Trap Venting

Category: infrastructure

The mechanical integration of a waste line vent stack to maintain water column targets inside a trap loop.

Every sink and shower must have a P-trap holding a column of clean water to block toxic sewer gases from venting into the home. Proper plumbing code venting ensures that when a large volume of water flushes down the line, it draws in atmospheric air from the roof stack rather than siphoning out the trap.

Common Examples

• A bubbling noise inside the bathroom basin sink indicated that inadequate P-trap venting was siphoning the water barrier clean away.
• Plumbing codes dictate strict maximum horizontal distance parameters between the vanity P-trap arm and the main vertical vent stack.