Demand site return flow links transmit wastewater from demand sites (DS) to destinations (Dest), which may be either wastewater treatment plants or receiving bodies of water. The amount that flows into the link is a fraction of demand site return flow (outflow minus the flow to demand sites for reuse).
DSReturnLinkInflowDS,Dest = DSReturnFlowRoutingFractionDS,Dest x DemandSiteReturnFlowDS
The amount that reaches the destination (i.e., the outflow from the link) equals the outflow from the demand site (i.e., the inflow to the link) minus any losses along the link.
DSReturnLinkOutflowDS,Dest = DSReturnLinkInflowDS,Dest - DSReturnLinkLossDS,Dest
The losses along the link are a fraction of its inflow, where the loss rates, both from the system and to a named groundwater node, are entered as data (see Supply and Resources\Return Flows\Losses).
DSReturnLinkLossDS,Dest = ( DSReturnLinkLossFromSystemDS,Dest + DSReturnLinkLossToGroundwaterDS,Dest ) x DSReturnLinkInflowDS,Dest