What is the purpose of a trap primer?

A trap primer serves the specific purpose of preventing the loss of water in a plumbing trap due to evaporation. Traps are designed to hold a small amount of water, which creates a barrier to harmful sewer gases. Over time, particularly in traps that are not used frequently, this water can evaporate, compromising the trap's function and potentially allowing sewer gases to enter the living space.

The trap primer automatically supplies water to the trap when it senses that the water level is too low, ensuring that a sufficient water seal is maintained. This operation is crucial for the effectiveness of the plumbing system, as a dry trap can lead to unpleasant odors and health hazards.

While other choices mentioned, such as siphoning water into the trap or enhancing drainage efficiency, may involve some considerations in plumbing, they do not directly address the primary function of the trap primer, which is specifically to maintain a water seal and prevent evaporation loss. Thus, maintaining that water level is vital for ensuring a safe and effective plumbing system.