What is the typical diameter of a residential drainage pipe?

The typical diameter of a residential drainage pipe is 4 inches. This size is commonly used for various drainage systems within residential settings, such as for wastewater and sewage lines. A 4-inch pipe effectively handles the volume of water and waste produced in a household while providing adequate flow capacity to prevent clogs and backups. Additionally, this diameter aligns well with standard plumbing fittings and fixtures used in home construction.

While smaller diameters, such as 1 inch and 2 inches, can be used for specific applications like sink drains or vent pipes, they are generally not suitable for main drainage systems. A 6-inch diameter might be used in larger residential systems or in commercial applications, but it is not typical for standard residential drainage. The choice of a 4-inch diameter pipe balances capacity needs with plumbing standards, making it the most common size for this application.