What is the purpose of an air admittance valve?

An air admittance valve serves a critical function in plumbing systems by allowing air to enter drainage systems, which helps to maintain proper pressure within the system and prevents the formation of a vacuum. This is essential for the effective flow of wastewater and prevents issues like siphoning, where water is drawn into the drainage pipes, potentially causing blockages or backups. By allowing air to enter, the valve ensures that wastewater can flow freely without interruption.

Other options do not accurately describe the role of the air admittance valve. While draining excess water, filtering air, or preventing water leaks are important aspects of plumbing systems, they do not relate to the specific function of regulating air pressure in drainage systems that the air admittance valve is designed for. This understanding is pivotal for ensuring that plumbing systems operate efficiently and effectively.