It is known that there are many factors which affect the removal of metals in conventional sewage treatment plant. The purpose of this research was the determination of ten metals (Fe, Cu, Zn, Mn, Pb, Cd, Cr, Ni, V, Li) in the wastewater of the town of Kavala (80,000 population), at the inlet and at the outlet of the waste water treatment plant under different conditions (strong rainfall, an average day and during holidays). The previously mentioned conditions showed the effect they have on the concentration of heavy metals in untreated waste water (the strong rainfall increases the concentrations of the Fe, Cu, Zn, Cr and Pb, and the holidays reduces the concentrations of the Fe, Cu, Zn, Mn, Ni, Pb and Cd) and the removal ability of metals during the treatment.