What is the main function of a plumbing vent?

The main function of a plumbing vent is to equalize pressure within plumbing systems. Vents allow air to enter the plumbing system, ensuring that water can flow freely without creating a vacuum that might hinder drainage. This is crucial for maintaining proper function in a plumbing system; without adequate ventilation, drains could become slow, gurgle, or back up entirely due to negative pressure.

The venting system serves additional purposes, such as preventing sewer gases from entering the building and providing a pathway for the release of gases that may be generated in the drainage system. However, the primary role is indeed to maintain or equalize pressure, allowing for smooth drainage and proper fixture operation.

Other choices refer to functions that are not directly related to venting. While supplying water to fixtures and removing waste are essential roles of the plumbing system, they are primarily handled by the pipes responsible for water supply and drainage, not by the vents. Draining stormwater runoff typically involves a different infrastructure entirely, focusing on managing surface water rather than the internal plumbing system.