Water networks incorporating a regeneration recycle can minimize freshwaterconsumption and wastewater discharge, to the extent of approaching the inherentminimum value. Based on the water network structure provided with internal watermains, this paper addresses the design methodology for water recycling with regeneration, andextends prior work to cases involving multi-contaminant systems. In such a structure water issupplied to each water-using process from freshwater main, regenerated water main, or regenerationwater main according to water quality. How to determine the contaminant concentrationsin the regeneration water main is the key in such a water network design. Theregeneration concentrations should be the lowest compatible with the freshwaterconsumption of the system equal to its inherent minimum value. The corresponding designmethodology focuses on how to determine which main to use as the water source and howmuch the water flow rate is to be for each water-using process, on the basis of mass balanceand the inlet contaminant concentration condition of that process. Finally, an example is givento illustrate the design method.