Abstract This work addresses a design of water network (WN), i.e. a subsystem consisting of water using processes and regenerators. A systematic approach was developed for synthesis and retrofit of WN. The method is based on superstructure optimization. To solve the problem adaptive random search optimization (ARS) technique was applied. The method accounts for water reuse, regeneration processes within WN and, also, for various optimization criteria as well as industrial requirements as, water losses and gains, fixed flow-rates and so on.