What is the purpose of a vent stack?

The purpose of a vent stack is to allow air into the drainage system and equalize pressure. This function is crucial in plumbing systems, as it helps prevent the formation of vacuum conditions that can disrupt the flow of wastewater. When water flows through pipes, it can create a negative pressure, which can lead to slow drainage or even the siphoning of water from traps. By providing a route for air to enter the system, a vent stack ensures that the pressure remains balanced, facilitating smooth drainage and reducing the risk of odors from sewer gases entering the living space.

In contrast, the other options focus on different functions that do not accurately describe the primary role of a vent stack. For instance, removing excess water from the system pertains more to drainage pipes, while draining sewage directly is the role of soil stacks and drain lines. Additionally, connecting to stormwater drains addresses another aspect of a plumbing system that is separate from the ventilation of the drain piping. Thus, understanding the role of a vent stack is essential for ensuring an efficient and code-compliant plumbing system.