We propose targets, based on real world data, necessary to design a financially viable microbial electrolysis cell (MEC) for the treatment of domestic wastewater. By reducing the cost of the anode and current collecting materials by 90%, a viable organic loading rate would be between 800 and 1,400g-COD/m(3)/d (2-3A/m(2)). The anode and current collector materials account for 94% of the total material costs; consequently, cost savings in any other material are moot. If the bioanode can be reused after 20 years, further, significant savings could be achieved. To develop targets we used real world data, for the first time, to evaluate the financial viability of MECs against the current predominant method of wastewater treatment: activated sludge. We modelled net present values for eight potential scenarios and the performances required for MECs to break-even. (C) 2018 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.