Measured absolute concentrations and the distributions of sedimentation rates (DSR's) of suspended solids (SS) and heavy metals in Combined Sewer Overflows (CSO's) show a strong variation between events. These variations can be explained partly by a relationship between the maximum discharge rate during an overflow and a) the concentrations of SS and the heavy metals Pb and Zn and b) the fraction of the DSR with high settling rates and the associated Pb concentrations. However, no unambiguous relationship between the DSR for the SS concentrations and the associated heavy metal concentrations has been detected. In contrast to the general experience a specific association of heavy metals with the fine fraction (low settling rates) in the SS of CSO's has not been found. The measured DSR's of SS and heavy metals have been used as input to a receiving water quality model. The simulated response is satisfactory, with regard to SS concentrations but not for heavy metals.