What is the purpose of a drainage system expansion joint?

A drainage system expansion joint is specifically designed to accommodate movement in piping due to thermal expansion and contraction. When temperature changes occur, materials can expand or contract, which may lead to stress and eventual cracking if there is no allowance for movement.

The use of expansion joints helps to maintain the integrity of the drainage system by ensuring there is flexibility built into the joints, allowing the system to adapt to internal and external pressures. This is essential to prevent damage and maintain proper functionality over time, particularly in environments with varying temperatures.

The other options describe functions that do not accurately match the primary role of an expansion joint; for example, enhancing the flow of wastewater focuses on hydraulic performance rather than structural integrity, while pooling water and noise reduction pertain to different design elements and considerations outside the function of an expansion joint.