Drain Slope Calculator (1/4 per Foot)

What slope do I need for a 4-inch sewer line?

A 4-inch building sewer under the IPC needs a minimum 1/8 inch per foot (1%), about 1 foot of fall per 100 feet, as long as the design maintains a 2 ft/s scouring velocity. Many jurisdictions and the UPC prefer 1/4 inch per foot for residential sewers — confirm with your local code before trenching.

Related questions

• What is the minimum slope for a drain pipe?
• Can a drain have too much slope?