What is the standard size for a residential drainage pipe?

The standard size for residential drainage pipes is primarily 3 inches. This size is commonly used for horizontal drainage systems, particularly for connecting fixtures like sinks, toilets, and tubs to the main drainage line. The 3-inch diameter effectively handles the typical volume of wastewater disposal in most residential settings, ensuring efficient drainage while minimizing the risk of clogs.

Larger diameters, such as 4 inches, are often used for the main sewer lines or for vent systems, while smaller sizes, such as 1 inch or 2 inches, may be found in specific applications like sink drains or small fixtures but do not meet the general requirements for overall household drainage. Therefore, 3 inches strikes an ideal balance for the various demands of typical residential plumbing.