This article is a study on final cleaning of wastewater in an experimental hydrophytic treatment plant. Wastewater was previously treated in a municipal wastewater treatment plant loaded with a significant amount of brewery sewage. This paper presents research results of the load of basic pollutants, a comparison between the effectiveness of treatment in vertical and horizontal flow plots and continuously or periodically flooded plots, the influence of brewery sewage inflow dynamics on both treatment effectiveness and treated sewage reaction. The results of the analysis indicate that the constructed wetland system is a relatively effective method. This system increases and stabilizes the efficiency of the wastewater treatment plant in Sierpc.