The paper assesses the costs of full-scale membrane bioreactors (MBRs). Capital expenditures (CAPEX) and operating expenses (OPEX) of Spanish MBR facilities have been verified and compared to activated sludge plants (CAS) using water reclamation treatment (both conventional and advanced). Spanish MBR facilities require a production of 0.6 to 1.2 kWh per m3, while extended aeration (EA) and advanced reclamation treatment require 1.2 kWh per m3. The energy represents around 40% of the OPEX in MBRs. In terms of CAPEX, the implementation costs of a CAS facility followed by conventional water reclamation treatment (physical-chemical + sand filtration + disinfection) ranged from 730 to 850 €.m-3d, and from 1,050 to 1,250 €.m-3d in the case of advanced reclamation treatment facilities (membrane filtration) with a capacity of 8,000 to 15,000 m3d-1. The MBR cost for similar capacities ranges between 700 and 960 €.m-3d. This study shows that MBRs that have been recently installed represent a cost competitive option for water reuse applications for medium and large capacities (over 10,000 m3d-1), with similar OPEX to EA and conventional water reclamation treatment. In terms of CAPEX, MBRs are cheaper than EA, followed by advanced water reclamation treatment.