This work addresses integrated water network synthesis problems by proposing detailed yet computationally efficient models for the design of membrane separation-based water regenerators. The resulting tighter formulation incorporates major physical parameters for the membrane regenerators. The resulting nonconvex mixed-integer nonlinear program (MINLP) based on a source-regenerator-sink superstructure is implemented on a case study and solved to global optimality using GAMS/BARON. © 2012 Elsevier B.V.