In both SewerCAD and StormCAD, a conduit can be designated as a diversion link by selecting "Is Diversion" as true. In a diversion conduit link the flow is determined by a flow diversion curve that specifies the flow amount diverted from the upstream node total inflow. The profile in the diversion link is then computed by gradually varied flow backwater calculations, using the downstream node hydraulic grade as the downstream control elevation, and working upstream.

The upstream hydraulic grade in a diversion link is the result of the backwater profile calculation moving up the diversion link, thus it has no impact on the upstream node hydraulic grade since the upstream node hydraulic grade is determined from the primary (non-diversion) conduit profile calculation, not the diversion profile. Because of such profile calculation treatment, sometimes a discontinuity of the diversion profile with the upstream node hydraulic grade can be observed (i.e. the profile at the upstream end of the diversion link will be different than the profile at the upstream end of the non-diversion link and the upstream node). Usually this difference is small.

If the diversion link’s upstream hydraulic grade is higher than the upstream node hydraulic grade, it indicates that either the diverted flow is too big or the diversion conduit is undersized. The reverse case is also true. For multiple diversions, such as those seen in a wastewater treatment plant, the multiple diversion profiles provide a clue to adjust the multiple diversion curves so that the resulting profiles are continuously connected to the upstream node hydraulic grade. If the upstream heads in the diversion links are significantly different than that at the upstream node, the user may wish to modify the flow split or modify the hydraulic characteristics of the system downstream of the split.