Increasing water demand by the process and allied industries coupled with global water stress and scarcity have underlined the importance of water as a crucial resource and increased the need for widespread adoption of water reuse and recycle. Early research based on water-pinch analysis addressed the use of systematic methods to identify the most promising opportunities for water reuse within a process plant. More recent work has addressed similar concepts in the framework of industrial symbiosis and Eco-Industrial Parks (EIP) under the assumption of the leadership of an EIP authority. However, many wastewater plants continue processing wastewater to condition water for disposal, which means meeting the limits given by regulations at a minimum cost. These wastewater treatment plants may play a role in a growing market of regenerated water in which an increasing number of businesses and public services would be demanding water with different quality specifications. Hence, this work is presenting an MINLP model aimed at exploiting the flexibility of a wastewater treatment plant and maximizing its profit within this market. Results and discussion are provided in regard of a case study based on a wastewater treatment plant nearby Barcelona.