Both freshwater consumption and wastewater discharge can be reduced significantly when wastewater regeneration recycling is introduced in the design of the water-using networks (WUNs). However, it is often difficult to design the WUNs involving regeneration recycling. This article presents an iterative method to design the WUNs involving regeneration recycling. The final designs can be obtained without iteration for the networks with known regenerated concentrations, and in a few iterations for the networks with known removal ratios of the contaminants. The method proposed can reduce the following parameters simultaneously, the consumptions of freshwater and the regenerated water, and the concentrations of the stream before regeneration, and all of them reflect the cost of the network involving regeneration recycling. The results of a few literature examples show that the designs obtained in this work are comparable to that obtained in the literature. The proposed method is simple and effective. (C) 2011 American Institute of Chemical Engineers AIChE J, 58: 456-465, 2012