Final answer:
A check valve should be installed on the sump pump discharge pipe to prevent backflow. This ensures efficient drainage and prevents water from returning to the pumped area.
Step-by-step explanation:
The discharge pipe on a sump pump should have a check valve installed to prevent previously pumped discharge from returning to the pump. A check valve is a one-way device that only allows fluid to flow in one direction, thus preventing backflow into the pump system. This is especially critical in a sump pump system to ensure that the water being pumped out of the area, such as a flooded basement, does not cycle back into the space which could overload the pump and lead to inefficient drainage or potential water damage.