When a backwater valve is installed in a subsoil drain system, it is required to be in a minimum diameter manhole of how many inches?

The requirement for a backwater valve to be installed in a minimum diameter manhole of 48 inches is based on principles of accessibility and functionality. A larger diameter ensures that there is sufficient space for maintenance personnel to access and service the valve easily.

In plumbing systems, especially those dealing with drainage and sewer systems, proper installation is critical to ensure that the backwater valve functions effectively to prevent sewage backup. The 48-inch manhole allows sufficient room for the installation of the valve itself, as well as additional space for maneuvering tools and equipment necessary for maintenance operations.

Choosing a manhole that is too small could lead to difficulties in accessing the valve during routine maintenance or in emergency situations, potentially compromising the system's overall effectiveness. Therefore, the standard of requiring a 48-inch manhole reflects best practices in plumbing design and maintenance to ensure safety and efficiency in managing wastewater.