What is the purpose of a Vent Stack in a DWV system?

The purpose of a Vent Stack in a Drain, Waste, and Vent (DWV) system is primarily to provide air circulation. This is crucial for maintaining proper atmospheric pressure within the plumbing system, which allows water to flow smoothly through the drainage pipes. Without adequate ventilation, negative pressure can occur when water drains, leading to slow drainage or even the complete cessation of flow. Vent stacks also help prevent the siphoning of water from traps, which is essential to maintain a water seal that prevents sewer gases from entering the living space. Proper ventilation helps ensure efficient drainage, enhances the performance of the system, and contributes to the overall health and safety of the plumbing infrastructure.