The composition of sediments formed in the process of pretreatment of stormwater is diversified and depends on many parameters, mainly on the quality of stormwater and the land use of the catchment. Stormater sediments are characterized by heterogeneous chemical and microbiological composition. The aim of this paper was the microbiological evaluation the sediments from four stormwater catchments in terms of hazard to humans and the environment. For the examined sediments, pH, and the content of organic and mineral matter were determined. Microbiological analysis included the determination of the total number of psychrophilic, mesophilic, and coliform bacteria, including E. coli, and also the number of faecal Enterococci, Salmonella and Shigella. The study was conducted for fresh deposits and those stored for one year in order to determine the dynamics of changes in their biological activity.