The integrated management of water resources has taken on great importance in recent years, especially in insular environments such as the Canary Islands and Madeira, which share geological, environmental, and economic characteristics. Nowadays, due to over-exploitation of aquifers, most of these islands cannot meet their water demand with the traditional resources, forcing their water authorities to establish conservation measures, including water reuse. Several water reuse schemes operate in islands with severe water scarcity, their main applications being in landscape and crop irrigation. However, islands with abundant groundwater resources consider reuse and the advanced treatment it entails as an environmental protection measure, rather than as part of a water saving strategy. This article analyzes the role of water reuse in the management of water resources in the Canary Islands and the Region of Madeira.