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

In the context of plumbing codes, the maximum number of water closets that can be supported by a 3-inch stack in a single-family dwelling is determined by factors such as drain size and the expected load on the plumbing system. According to the plumbing code, a 3-inch vertical stack is typically designed to accommodate two or three water closets, subject to distances and certain conditions.

Having three water closets connected to a 3-inch stack helps ensure proper drainage without risking clogs and backflow issues. This number is also based on considerations of venting, which is crucial for maintaining air pressure in the system and allowing wastewater to flow smoothly.

Exceeding this number could lead to excessive waste build-up, increased chances of blockages, and inadequate venting, which can ultimately disrupt the plumbing system's performance. Therefore, aligning with the plumbing code, three water closets is the correct and safe practice for plumbing design in single-family dwellings.