Which is the maximum number of water closets allowed on a 3 inch stack in a single family dwelling?

The maximum number of water closets allowed on a 3-inch stack in a single-family dwelling is based on plumbing code specifications. According to these standards, a 3-inch stack can adequately service up to three water closets. This is due to the capacity and flow rate that a 3-inch diameter pipe can handle. Each water closet contributes to the load on the stack, and maintaining proper drainage and venting is crucial for the system's efficiency and to prevent issues like overflow or inadequate flush.

A stack larger than 3 inches is typically required for larger installations that need to accommodate more fixtures. Therefore, one might find that options indicating four or five water closets would exceed the capabilities of a 3-inch stack and fall under codes designed to prevent plumbing system failures. The constraints set by relevant plumbing codes ensure that the water closets can function effectively without causing drainage problems or unnecessary strain on the plumbing system.