Pipe Capacity Calculator
What is the flow capacity of a full-flowing lateral or main pipe?

Pipe capacity depends on the diameter, material, and grade of the pipe.

Manning's roughness coefficient (n):

For smooth-wall inside corrugated plastic, n=0.012

For 4, 5 and 6-inch single-wall corrugated plastic, n=0.015
For 8-inch single-wall corrugated plastic, n=0.016
For 10-inch single-wall corrugated plastic, n=0.017
For 12 and 15-inch single-wall corrugated plastic, n=0.018
For 18 and 24-inch single-wall corrugated plastic, n=0.020

For clay or concrete drain tile, n=0.013

Source: Corrugated Polyethylene Pipe Association (2000) and ASABE EP260.5 FEB2015 (R2019)

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