A systematic approach using the graphical representation of water use and its system-wide manipulation is proposed for minimising freshwater and wastewater generation for discontinuous water systems. Design interactions of time-dependant water reuse and implications of storage tank in the network design have been fully addressed, and a new targeting and design method has been proposed to provide guidelines for achieving minimum freshwater requirements and to design the configuration of water re-use networks. Design complexity associated with simultaneous consideration of concentration and time constraints has been effectively dealt with in the proposed design method, which clearly provides benefits by reducing water consumptions and maintaining sustainable water usage. (C) 2011 Elsevier B.V. All rights reserved.