What is the purpose of the plumbing vent system?

The plumbing vent system is primarily designed to provide sufficient air for drainage fixtures in order to ensure that wastewater can flow freely through the drainage pipes. When water is drained from a fixture, it creates a vacuum or negative pressure in the pipes. Without proper ventilation, this vacuum could hinder the flow of water, potentially causing slow drains or even siphoning of water from traps, which are vital for preventing sewer gases from entering the building.

By allowing air to enter the plumbing system, the vent helps maintain neutral pressure, enabling the smooth flow of wastewater and ensuring that traps remain filled with water, effectively blocking sewer gases. This function is critical for the overall efficiency and safety of a plumbing system.