What phenomenon can cause a trap to lose its water seal?

A trap losing its water seal can primarily occur due to evaporation. Traps are designed to hold a specific amount of water, creating a barrier that prevents sewer gases from entering the living space. However, if a fixture connected to the trap is not used for an extended period, the water in the trap can evaporate. This is especially common in seldom-used bathrooms or fixtures, where the standing water can dry up, thus breaking the seal.

The presence of water in the trap is crucial for maintaining the seal between the sewer line and the interior of the building. Once evaporation occurs and the water level drops, the trap no longer functions as intended, allowing odors and gases from the sewer to escape into the building. Regular use of all fixtures helps prevent this phenomenon by ensuring that the water in the traps remains at a sufficient level.

Understanding evaporation as a cause for losing a trap's water seal highlights the importance of maintaining regular use of plumbing fixtures to prevent potential issues with sewer gas intrusion.