If a fixture trap has excessive outlet distance or the pitch is excessive, what could occur?

A fixture trap with excessive outlet distance or excessive pitch can lead to the phenomenon known as self-siphonage. This occurs when the slope of the drain line is too steep or the distance from the trap to the vent is too great, causing the water in the trap to be siphoned out too quickly. As a result, air can enter the trap, breaking the water seal that prevents sewer gases from entering the building.

Maintaining proper pitch and outlet distance is crucial for effective drainage and venting. If the slopes are too steep, they can create a suction effect that draws water out of the trap more rapidly than it can be replenished, leading to self-siphonage. This not only allows unpleasant odors to escape into the living spaces but can also compromise the functioning of the plumbing system.

Understanding this mechanism is essential for maintenance and ensuring that drainage systems operate efficiently and safely.