A common name appurtenance used to keep an accidental flow of wastewater from entering a building is called?

• A. Barrel
• B. Cleanout
• C. Backwater valve
• D. Catch basin

Answer: (C)

Preventing wastewater from flowing back into a building during a sewer backup is the function being tested. A backwater valve is installed on the building sewer line and is designed to let wastewater leave the building while automatically closing if sewer pressure from the municipal system pushes water back toward the building. This one-way flow stops an accidental backup from entering basements or lower floors. The device typically uses a flap or gate that remains open during normal flow but seals shut when backflow occurs. A cleanout is just an access point for cleaning pipes, not a backflow barrier. A catch basin collects surface runoff, not sewer backups. The backwater valve is the appropriate device for preventing backflow into a building.