This paper investigates the efficacy of time-lapse electrical imaging using surface electrodes to monitor the movement of leachate within a landfill. A laboratory-based study allowed direct comparison between observed physical dewatering and time-lapse electrical imaging data. In combination with a forward modelling study this demonstrated the limitations and advantages of this geophysical technique in terms of its applicability, resolution and complementarity to conventional dewatering monitoring techniques. It also confirmed the nature, likely magnitude and impact of artefacts created by the resistivity inversion process and highlighted the potential for misinterpretation of results. An 18-month study provided field results comparing hydrogeological and imaging data during the dewatering of a real landfill system. Insights gained from the laboratory study and forward modelling exercise greatly enhanced the interpretation of the field data, enabling the method to be applied with greater confidence in the future. The need to combine a forward modelling exercise with any interpretation of resistivity data is clearly demonstrated.