What is a common effect of improper venting in plumbing systems?

Improper venting in plumbing systems can lead to trap siphoning and the potential for sewer gas to enter buildings, which is a significant concern for health and safety. Vents are designed to allow air to enter the plumbing system and equalize pressure within the pipes. When there is insufficient venting, it creates negative pressure, which can cause water traps to be emptied or siphoned out. These traps are crucial for preventing harmful sewer gases from entering the living spaces.

Without adequate venting, the water in the traps can be pulled out by the pressure changes, allowing the unpleasant and hazardous sewer gases to breach the building's interior. This not only creates a foul odor but can also pose serious health risks to the inhabitants. Maintaining proper venting is essential to ensure that traps remain filled with water, thereby serving as an effective barrier against harmful gases.

The other options present scenarios that may sound beneficial, but they do not directly address the critical function of venting and the repercussions of its inadequacy, emphasizing why trap siphoning and sewer gas problems are the correct focus.