Which of the following materials is NOT commonly used for drainpipes?

The choice of wood as a material for drainpipes is not common due to several inherent disadvantages. While wood has traditional uses in construction, it's not well-suited for underground or continuous exposure to moisture, which is typical for drainpipe applications.

Wood is susceptible to rot, pests, and degradation from water exposure, making it an unreliable choice for a material that needs to maintain structural integrity over time. In contrast, materials like PVC, concrete, and clay are specifically designed to withstand moisture, resist corrosion, and provide durability in various conditions, making them the standard choices used in drainpipe installations.

PVC is lightweight, easy to install, and resistant to chemical corrosion. Concrete provides strength and durability for large-scale drainage systems, while clay has a long history in drainage due to its durability and ability to hold shape under pressure. Therefore, wood is not practically used for drainpipes in modern drainage systems.