Which types of materials are typically prohibited in drain, waste, and vent (DWV) systems?

In drain, waste, and vent (DWV) systems, the materials used must meet specific requirements to ensure optimal performance, durability, and safety. Galvanized steel is often prohibited in some plumbing applications due to its susceptibility to rust and corrosion over time, which can lead to leaks and system failure. Certain plastics may also be restricted in DWV applications because they may not withstand the temperature fluctuations or chemical exposure that can occur in such systems.

In contrast, other materials, such as copper and brass, are usually acceptable due to their corrosion resistance and strength. PVC and ABS plastic are commonly used in DWV systems because they offer several advantages, including resistance to chemicals, lightweight properties, and ease of installation. Concrete and glass, while they have their own applications, are not typically utilized in standard DWV systems due to issues related to weight, flexibility, and potential breakage. Therefore, the choice of galvanized steel and certain plastics as prohibited materials aligns with the code's emphasis on reliable and durable plumbing systems.