What Is the Minimum Sewer Pipe Slope?

The calculation used to calculate the slope of the sewer pipe drain is S={V/[1.486/n*(D/4)^(2/3)]}^2. Slope is useful in draining sewer pipes because is is calculated to provide a minimum cleansing velocity for when the pipe is at a full flow or half flow. The minimum velocity is typically two to three feet per second. For larger pipe diameters, other considerations, such as ground subsidence may be evaluated in the calculations.