The results of research on the influence of soil fertilization with preliminary sediments (150 Mg ha-1 d.m.) on the soil solution composition and underground water are presented in this work. The quality of infiltrating waters was increasing together with increasing depth. The usage of preliminary sediments coming from the sewage treatment might cause underground water pollution with nitrate because the concentration of this nitrogen form in the soil solution increases even up to 43.7 g N-NO3 m‑3. Higher nitrate concentration is to be seen in infiltration water than in capillary rise. The chemical composition of the soil solution shows that waters which head for the ground surface contain less pollution components than waters which infiltrate from the surface to underground waters. The investigated heavy metals sometimes show different proprieties – some of them enter easily into the soil solution, while others are permanently bound in the exchangeable soil sorption complex.