The present paper reviews water reuse applications around the world, particularly focuses on reuse practices in the Mediterranean countries, and also describes experimental and real case studies on the use of biologically treated wastewater and sewage sludge in Greek and Turkish forest areas. From the reviewed examples, it is evident that the safe reuse of treated urban wastewater (for different purposes depending on the priorities of the country) is not only a priority task in those countries facing serious water scarcity problems, but is also being practiced in many industrialized countries for many years. Pilot-scale studies carried out in Greece on various plant species indicated that critical parameters, such as crop tolerance and absorption capacity for different heavy metals, differ from plant to plant and also depend on the metal concentration as well as the relative ratio of the heavy metals to each other. On the other hand, some preliminary intentions in Turkey regarding the reuse of biologically treated wastewater originating from Turkish urban wastewater treatment plants for forest land irrigation were also demonstrated in the present paper. The detailed data inventory devoted to the search for related case studies in other Mediterranean countries and around the world revealed that the proposed methodology of treated wastewater reuse in reforestation could be further developed in the nearest future, positively contributing to the protection of the environment as well restoration of the landscape and of public areas.