Municipal water reservoirs improve urban landscape architecture, providing water for various domestic uses. At the same time, they are under strong human impact affecting water quality and biological conditions. We investigated the level of metal accumulation (Cd, Co, Cr, Cu, Fe, Ni, Mn, Pb and Zn) in sediments as well as mussels Anodonta anatina and Unio tumidus and common reed Phragmites australis collected from 8 sampling sites at Malta Reservoir (Poznań, Poland) just before the complete drainage of the lake in November, 2012. In all investigated samples metal concentrations ranked in decreasing order: Fe > Mn > Zn > Cu > Cr > Ni > Pb > Co > Cd. Accumulation of toxic metals in roots of P. australis was higher than in soft tissues of mussels although it did not exceed phytotoxic levels. Roots of P. australis accumulated high levels of Cr (mean 9.7 μg g⁻¹) and Ni (mean 5.7 μg g⁻¹). U. tumidus accumulated higher concentrations of Cr (mean 1.1 μg g⁻¹) than A. anatina indicating potential use in bioindication of this metal. The present study provides the most recent information on metal content in sediments and biota in Malta Reservoir and, further, suggests that this reservoir is capable of accumulating toxic elements from preceding water bodies (Lake Swarzędz) and surrounding residential areas.