What is the purpose of the check valve in the discharge line from a sewage ejector pump?

The purpose of a check valve in the discharge line from a sewage ejector pump is primarily to prevent backflow. In sewage systems, backflow can occur when there are changes in pressure in the discharge line or if there is a clog downstream. The check valve allows fluid to flow in one direction—away from the pump—while preventing any returned flow back into the sewage ejector pump. This function is crucial to maintaining the efficiency and effectiveness of the sewage disposal system, ensuring that waste is properly expelled and does not re-enter the system.

In contrast, while controlling flow rate, regulating pressure, or minimizing odors are important functions within plumbing systems, these are not the primary roles of a check valve. Flow rate is typically managed by sizing the discharge pipe and adjusting the pump's operation, pressure regulation is often handled by specific pressure valves, and odor management usually involves venting and proper trap design. Thus, the key function of the check valve is its role in protecting the pump and plumbing system from undesirable backflow conditions.