In this study a tool for the calculation of costs of different wastewater treatment and reuse scenarios has been developed. This tool, called Evaluation of Wastewater Treatment and Reuse Option (E-WA-TRO), was designed to have as end-users public administrators, water management authorities, and professionals that, in a direct and immediate manner, can automatically obtain, for a particular reuse alternative, the fundamental information for a feasibility study. In order to develop E-WA-TRO an overview was conducted of the international, national and regional regulations on water reuse and a synopsis of the possible reuse alternatives and of the appropriate treatment processes was prepared. Moreover, costs were obtained using national and international published data for the different treatment processes that might be required for the various reuse alternatives. The system has been created as a web site, in order to guarantee the highest availability and a wide diffusion and the possibility of an easy implementations of future updates and upgrades. Specifically, even non-expert user can easily navigate trough the site and use the tool to evaluate, within the national and international legal frameworks, various reuse alternatives as well as the appropriate treatment technologies and related costs.