Water shortages have a direct impact on the life of many mining and mineral processing operations. Therefore, a good understanding of the effects of water quality on flotation performance is essential. In this study, effects of dissolved ions (both anions and cations) were investigated on the flotation performance of a Cu-Zn complex sulfide ore from Cayeli Bakir Isletmeleri A.S. (CBI) (Turkey) by means of batch flotation tests. The results of the flotation tests revealed that accumulation of dissolved metal ions and sulfide ions, mainly in the form of SO42- and S2O32-. changed both the froth stability and surface chemistry of the sulfide minerals. The froth stability and hence the recovery by entrainment, increased in conjunction with the dissolved ion concentration in water. The presence of dissolved metal ions, such as Cu2+ and Pb2+, also increased the flotation rate and recovery of sphalerite. In the case of pyrite, the activation by dissolved metal ions was observed for moderately contaminated recycled water samples. High concentrations of sulfide ions however, counteracted the activation effect and reduced the recovery of pyrite by true flotation. (C) 2011 Elsevier B.V. All rights reserved.