What is the purpose of a backwater valve in a plumbing system?

The purpose of a backwater valve in a plumbing system is specifically to prevent sewage from backing up into the building. When there is a blockage in the sewer line or during heavy rain events, wastewater can flow back towards the home. The backwater valve acts as a one-way valve, allowing wastewater to flow out of the building but preventing it from flowing back in. This is crucial for maintaining sanitary conditions within the home and safeguarding against potential contamination and extensive damage caused by sewage backup. It ensures that the plumbing system functions effectively, especially in areas prone to flooding or where the sewer system is at risk of being overwhelmed. In contrast, the other options refer to different functionalities that do not pertain to the specific role of the backwater valve.