FREEWAT’s main result is an open source and public domain GIS-integrated modelling environment (the FREEWAT platform) for the simulation of water quantity and quality in surface water and groundwater with an integrated water management and planning module. FREEWAT is a composite plugin for QGIS, designed as a modular ensemble of different tools, including for analysis, interpretation and visualization of hydrogeological and hydrochemical data and quality issues, for simulation of models related to the hydrological cycle and water resources management, or for performing model calibration