The treatment of wastewater in small rural settlements requires special attention in the choice of the purification technique to be used, insofar as experience has shown that the technologies initially developed for the urban environment do not prove to be as effective for the rural environment. The current trend tends towards autonomous systems. Among these systems: Floating treatment wetlands. The objective of this study is to evaluate the evapotranspiration and the performances of two emerging plants; Cyperus papyrus and Typha latifolia. The experimental device is composed of three test tanks whose dimensions are: length = 1m, width = 1m and water height = 0.85 m. Two tanks with emerging plants (Cyperus papyrus and Typha latifolia) and a control tank without vegetation. The monitoring of the evolution of plant evapotranspiration and the evaporation of the control tank for different periods and temperatures showed that the volumes of water lost are respectively for Cyperus papyrus, Typha latifolia and control tank : - 130 liters, 230 liters and 5 liters for two days at an average temperature of 26.3 °C, - 125 liters, 150 liters and 0 liters for two days at an average temperature of 26.7 °C, - 240 liters, 280 liters and 5 liters for three days at an average temperature of 27.3 °C, - 140 liters, 260 liters and 10 liters for two days at an average temperature of 26 °C, - 140 liters, 240 liters and 5 liters for two days at an average temperature of 27.3 °C, - 260 liters, 550 liters and 10 liters for four days at an average temperature of 28.6 °C. It turned out that the presence of plants as well as the temperature and the retention time in the tanks have a impact on the loss of water and more precisely those with emerging macrophytes. The present study has shown that the floating treatment wetlands planted with Cyperus papyrus and Typha latifolia can be used for wastewater treatment. Indeed, the removal efficiency in terms of COD, BOD5 and SS were respectively: 76%, 75.3% and 95.90% for Cyperus papyrus and 70.45%, 66.5% and 93.70% for Typha latifolia.