Illinois Plumbing Code Practice

What is the minimum diameter required for any portion of the drainage system installed underground or below a basement or cellar?

1. 1 inch

2. 1.5 inches

3. 2 inches

4. 2.5 inches

The correct answer is: 2 inches

In plumbing systems, the minimum diameter for drainage pipes is a critical factor for ensuring effective waste flow and preventing blockages. According to the Illinois Plumbing Code, the minimum diameter required for any portion of the drainage system installed underground or below a basement or cellar is indeed 2 inches. This size allows for adequate removal of waste and drainage, while minimizing the risk of clogging due to the size and potential volume of material that needs to be conveyed through the system. Larger diameters also help accommodate the additional pressure and potential for debris that can accumulate in underground installations. Smaller diameters, such as 1 inch or 1.5 inches, are often insufficient for the needs of a drainage system in these environments, potentially leading to backflow or slower drainage rates. Therefore, establishing a minimum of 2 inches is a practical and necessary standard to ensure the effectiveness and reliability of the plumbing system.