A shower room with multi-shower heads shall be serviced by a minimum 3-inch drain for each how many valves or heads?

The correct choice indicates that a minimum 3-inch drain is required for each 10 shower heads or valves in a shower room. This requirement ensures adequate drainage capacity to handle the volume of water that could potentially flow from multiple shower heads simultaneously, preventing issues such as overflow or backflow.

In a multi-shower setup, proper drainage size is critical to maintain hygiene and ensure that the drainage system operates effectively without blockage. A 3-inch drain serves as an appropriate solution for this scenario, accommodating the concurrent use of showers while adhering to plumbing code regulations.

In contexts where there are fewer than 10 shower heads or valves, smaller drain sizes may suffice, but as the number of shower heads increases, so too does the necessity for a more robust drainage solution to handle the increased wastewater output. This standard helps to keep the plumbing system functioning efficiently and safely.