A quick note: A really nice feature of the way #SWMM5 models water quality is the easy ability to model tracers for the contribution of the major processes. You can set up a concentration of 100 (for example) for DWF, RDII Flow, Runoff and Groundwater to find the percentage contribution of the process in link flow.

For example, if you model RDII using the RTK UH procedure the percentage of the RDII Water Quality Constituent is the flow from the upstream RDII nodes. This technique can be used to show how important DWF, Separate Sewersheds and Combined Sewersheds to the WWTP flow or Outfall flow.

The following two images are from the Innovyze Products InfoSWMM and InfoSWMM SA

How to define the RDII Concentration in the Pollutant Dialog

RDII Tracer Concentration over time