When eductor trucks are used to maintain catch basins, the mixture of water and sediment that is produced has to be disposed of in some way. This paper considers the quality of this mixture after it has been discharged from the eductor truck. The results show that the metal concentrations varied more in the water phase than in the sediment phase and that most of the metals were attached to particles. No significant difference could be found in the water between a housing area and a road, whereas a significant difference could be found for Cr, Cu, Ni, and Zn in the sediment at a 95% confidence level. The smallest fraction (<63 µm) in the sediment had the largest concentration of metals. Sampling procedure, time, and traffic intensity had an impact on the particle-size distribution. The water exceeded the guidelines for all studied metals; however, the concentration for the water will be affected by the wash water volume, whereas, for the sediment, only copper exceeded the guidelines.