Where \(C_{k,SR\_ref}\) is the concentration of a reference source. In the example above, the reference source should be source 2 when the flowrate for source 1 is to be determined. Otherwise, if the flowrate of source 2 should be determined, then source 1 should be used as the reference source.
The freshwater reduction by reducing the flowrates of the sources is only possible when the Pinch Point occurs at the non-limiting contaminants. For example, if the Pinch Point occurs at the contaminant ’A’ after shifting the source CC in Figure 5a, the freshwater requirement is already at the optimum level. There is no room for further reduction. The ratio with the sink’s concentration with the maximum source concentration ratio can be used as the indicator to determine the limiting contaminant for the specific sink (see Section 2.2.1).