Economic evaluation was carried out for a plant of fluoride removal by nanofiltration having a capacity of 2400 m(3)/d (100 m(3)/h) corresponding to a water consumption for 50.000 capita following the Moroccan considerations in rural medium. The design of this plant was carried out for the predetermined optimized conditions corresponding to a recovery rate of 84%, a fluoride rejection of 97.8% and a pressure pump of 10 bar. The capital cost was estimated to 748,003(sic) and the calculated operating cost to 0.212 (sic)/m(3). These costs were briefly compared to other ones. (C) 2009 Elsevier B.V. All rights reserved.