Many countries have the problem of a severe water imbalance. This imbalance in water demand vs. supply is due mainly to the relatively uneven distribution of precipitation, high temperatures, increased demands for irrigation water and the impacts of tourism. To alleviate water shortages serious consideration must be given to wastewater reclamation and reuse. In this paper, some good examples of the potential benefits of wastewater reuse in different countries are presented, giving special consideration to the costs associated with the processes. Naturally, they are most obvious for the arid areas but the general increasing pressures on water resources all over the world should also make wastewater reuse attractive in other areas. The criterion for selecting these cases has been the contribution of the system into the overall increase of wastewater reuse in the country implemented. The effect of potential success factors and parameters has been looked into in order to realise why the implementation of these systems was proven to be highly efficient and successful.