A shower room having 8 multiple-shower valves shall be serviced by a minimum _________ inch drain.

In plumbing codes, the sizing of drains for fixtures is crucial for ensuring proper drainage and to avoid issues such as backups or inadequate flow. For a shower room with multiple shower valves, the drain size needs to accommodate the cumulative flow from all the fixtures.

In this specific scenario, a shower room with 8 multiple-shower valves typically requires a drain size that ensures efficient disposal of wastewater. A drain diameter of at least 3 inches is specified because it has the capacity to handle the flow from multiple showers simultaneously without becoming overwhelmed. This size allows for the proper hydraulic performance needed in a high-demand situation like several showers operating at once, maintaining adequate drainage.

A 2-inch drain, while commonly used in smaller systems or for fewer fixtures, does not provide sufficient capacity for the volume generated by 8 shower valves. Increasing to a 4-inch drain might be seen as excessive for this scenario, since the 3-inch option is specifically designed to meet the expected needs without unnecessary over-sizing. Therefore, the correct answer aligns with standard plumbing practices and the regulations set forth in the Omaha Plumbing Code for such installations.