What is the name of the pipe that serves as both the inlet and outlet to an elevated tank?

The correct answer is the riser. A riser is a vertical pipe that connects an elevated tank to the distribution system, functioning as both the inlet and outlet for the water stored in the tank. This dual functionality is essential for supplying water from the tank to the distribution network while also allowing for water to be drawn into the tank for refilling purposes.

The design of the riser enables it to handle changes in pressure and flow, making it a crucial component in maintaining the circulation and availability of water in a distribution system. Its strategic placement allows for efficient water management, ensuring that higher elevation does not hinder the supply pressure required for effective distribution.

Other terms like feeder, discharge pipe, and drainage pipe refer to different roles in a water distribution system. A feeder typically refers to a pipe that supplies water to a specific area or point, while a discharge pipe usually conveys water away from a system, often in the context of releasing from pumps or other mechanisms. A drainage pipe is specifically designed for removing excess water or rainfall, not for the purpose of supplying and retrieving water from a tank. Thus, the riser is the most accurate term for a pipe that serves as both an inlet and outlet to an elevated tank.