How Many DFUs Can a 3 Inch Drain Carry?

A 3 inch drain pipe is commonly used for toilets, branch drains, and building drains. Maximum allowable fixture unit capacity depends on plumbing code, slope, and configuration.

Factors That Affect Capacity

• UPC vs IPC code requirements
• Horizontal vs vertical installation
• Drain slope
• Building drain vs branch drain classification

Detailed interactive sizing calculator coming soon.