Water reuse is becoming increasingly important in the context of sustainable construction. Currently, the increase in demand and decrease in the supply of quality water is one of the problems that has been affecting large urban populations in particular. In this context, there is a need to encourage practices, programmes and policies that help conserve water. Water reuse is a strategic activity and an important tool in the integrated management of water resources. In view of the above, there is the possibility of using sanitary wastewater for irrigation purposes. The general aim of this work was to develop an ecological system for the treatment and agricultural use of sanitary wastewater in the semi-arid region of Rio Grande do Sul, in order to mitigate the possible environmental impacts caused. It consists of a septic tank with two chambers, a constructed flooded system with elephant grass as the extractor plant and a solar reactor.