The main objective of this study is to compare the impacts of alternative water policy management scenarios on Tunisia and Morocco. A dynamic water CGE-model has been implemented and used to explore the likely effects of water economic instruments. Results show that the low cost of water has encouraged farmers to adopt more water-intensive activities. Reducing public subsidies on water will affect directly farm income which is expected to drop by about 20 per cent in the short and medium terms. However, the reduction of farmers’ incomes will be largely compensated by the saving in public expenditures but also in a better and more efficient use of water resources.