Medium consumption is a significant component of the cost of operating a dense medium plant. This study aimed to identify and quantify many of the factors contributing to overall consumption through extensive surveys of four widely differing dense medium mineral separation plants, and associated laboratory experiments. Particular attention was given to the effect of operating density on medium loss. It was concluded that quite modest increases in operating density significantly increased loss from all sources. Density should therefore be minimised, commensurate with process requirements. There is also unequivocal evidence that consumption increases significantly with plant downtime, probably due to housekeeping wastage and overloading of regeneration circuits during the return of dumped medium to circuit. Other conclusions related to the effects of feedrate, ore porosity, medium viscosity, screen washing configuration, screen drainage efficiency and medium size on medium loss. Recommendations for operating practice are given.