What is the minimum horizontal developed length allowed between the outlet of a water closet and the connection to a double sanitary tee pattern?

The minimum horizontal developed length of 18 inches between the outlet of a water closet and the connection to a double sanitary tee pattern ensures proper drainage and venting. This distance is critical to prevent any issues with sewer gases and to maintain an efficient flow of waste. A sufficient distance helps to create a trap seal, preventing the backflow of sewage and ensuring that the water closet operates effectively. Additionally, this spacing helps to minimize potential clogs and facilitates maintenance access.

Understanding the requirements for plumbing installations, such as these minimum lengths, is essential for ensuring compliance with building codes and promoting functionality within plumbing systems. It also reflects best practices in plumbing design, where adequate distances improve the overall performance and reliability of the system.