A shower waste shall run independent of other fixtures directly to a _______ inch or larger waste.

In plumbing systems, particularly for drainage, it is essential that certain fixtures, such as showers, have their waste lines sized appropriately to ensure efficient drainage and to avoid clogs. A shower waste must run independently to accommodate the flow of wastewater generated by the shower without interference from other fixtures.

The correct answer, which is 3 inches or larger, is specified because a minimum pipe size of 3 inches allows for adequate drainage capacity. This size is sufficient to carry the volume of water typically discharged by a shower, thus preventing backflow and ensuring that the waste is effectively disposed of into the main sewer line. Additionally, using a 3-inch waste line promotes better airflow within the plumbing system, reducing the likelihood of siphoning or drainage issues that could occur with smaller piping.

Larger sizes, like 4 or 5 inches, while also acceptable, may not be necessary for a shower waste line alone. However, the minimum requirement set at 3 inches ensures that the system is designed effectively to handle the waste load efficiently.