The water management in the batch process industries has been optimised considering the reuse of water effluents in the same plant through storage tanks. For a given production plan, the characterisation of the water streams associated to the different production tasks is established. The connections between the available tanks and the water streams have been determined targeting different aspects: freshwater demand, water cost, utility demand of water streams and water reuse network costs. The water reuse system has been modelled, simulated and optimised. A software tool has been developed that permits an easy application of the methodology.