What is the smallest diameter of pipe that should be used for floor drain waste lines?

The smallest diameter of pipe that should be used for floor drain waste lines is 2 inches. This size is typically established based on plumbing codes and best practices, ensuring efficient drainage and preventing blockages. A 2-inch diameter provides an adequate flow rate for the waste generated from floor drains, accommodating potential sources of waste and water from various fixtures in a building.

Using a diameter smaller than 2 inches can lead to inadequate drainage, increasing the risk of clogs and backups, especially when considering the volume of water that might enter the system during heavy use. This standard helps promote the longevity of the plumbing system and reduces maintenance issues related to waste flow.