This article investigates the efficiency of using energy willow (Salix spp.) as a component of phytofiltration systems for reducing nitrate concentrations in the Vereshchytsia River catchment. The relevance of the study is driven by the increasing diffuse nitrate contamination of surface waters in agricultural regions and the need to implement nature-based purification methods. Experimental studies were conducted under laboratory conditions using a model soil-plant filtration system. Model solutions contained nitrates at concentrations of 10, 25, and 50 mg/L. Nitrate concentrations in the water were determined by the photometric method before and after passing through the system. The results demonstrated that the presence of energy willow in the filtration substrate ensures a significant reduction in nitrate concentrations in the filtrate. The purification efficiency increased with longer contact time between the solution and the substrate, reaching 45÷60% after 24 hours. The obtained results confirm the potential of using energy willow in nature-based water purification systems for nitrate contamination reduction in the Vereshchytsia River catchment.