Paper’s objective was to provide a critical overview of the current state of wastewater generation in different processes around the world  and their use in irrigation. As a follow-up, a brief overview of the classification of wastewater  and its potential for end use is presented.  Furthermore, a specific overview  of irrigation using wastewater  is presented, together with the relevant scientific papers in which the research on waste- water  irrigation impacts on the plants, soil, humans, and the environment are studied. Finally, a special reference  was given to the guidelines and policies proposed by the EU stakeholders regarding the integration of wastewater  reuse into water planning and management in the context of circular  economy, with special  emphasis put on novel technologies.