What type of durable pipe material is commonly used in older buildings for waste and drainage systems?

The selection of cast iron pipe as the correct answer is well-founded based on its historical significance and durability in waste and drainage systems. Cast iron pipes have been utilized in building construction for over a century due to their robustness and ability to withstand significant internal and external pressures. They are particularly suited for below-ground installations, where they are less prone to degradation from soil conditions and corrosion compared to other materials.

Cast iron's strength allows it to support heavy loads, making it ideal for wastewater applications where settlement or subsidence might occur. Additionally, cast iron has favorable acoustical properties, which help in reducing the noise from flowing wastewater, a key consideration in building design.

In the context of older buildings, cast iron was the predominant choice long before modern alternatives like plastic or PVC became popular. While newer materials such as plastic and PVC pipes offer lighter weight and corrosion resistance, they have not been used as extensively in buildings constructed before the mid-20th century when cast iron was more common. As a result, cast iron is often identified as the traditional material for waste and drainage systems in older structures.