Which material is commonly NOT used for drainage systems?

The choice of glass as a material for drainage systems is generally not common due to a few critical reasons. Glass is brittle and can easily break, which makes it unsuitable for the infrastructure typically required in drainage systems where flexibility and robustness are essential. In addition, glass does not have the durability or flexibility to withstand the pressure and stresses that a drainage system may encounter.

In contrast, materials like PVC, cast iron, and copper are widely used in drainage systems. PVC is favored for its lightweight, corrosion resistance, and ease of installation. Cast iron, while heavier, is highly durable and has excellent resistance to impact, making it suitable for underground sewer systems. Copper, although more expensive, is used in specific applications due to its antibacterial properties and resistance to corrosion. Each of these materials is specifically chosen for their properties that align well with the requirements of drainage systems, whereas glass does not meet those practical needs.