What is described as a necessary feature for the outlet pipe of an ejector?

For the outlet pipe of an ejector, incorporating a backwater valve is essential because it is designed to prevent backflow of sewage or waste into the ejector pit. Ejectors are typically employed to pump sewage or wastewater from lower elevations to higher elevations, and a backwater valve serves as a safeguard. It ensures that during times of heavy rainfall or sewer backup, the flow of water does not reverse and enter the ejector basin, which could lead to overfilling and cause health hazards or equipment damage.

In contrast, while check valves are also used in plumbing systems to prevent backflow, they are generally installed directly on the discharge side of the ejector pump, not specifically designed for the outlet pipe in the way that a backwater valve is. A sump basin is where an ejector pump is installed and does not address the backflow issue on its own. A floating switch is a component used to activate the pump based on water levels but does not contribute to preventing backflow. Thus, the necessity of a backwater valve for the outlet pipe of an ejector aligns with the primary function of maintaining a safe and efficient wastewater management system.