Multidimensional assessment of the safety and efficiency of reclaimed water use for irrigation

The aim of this study was to evaluate the safety and agronomic effects of using reclaimed water recovered from urban wastewater for plant irrigation under controlled greenhouse conditions in four North/Central European countries. While water reuse for irrigation is widely implemented in regions with hot climates, its adoption in Northern and Central Europe remains limited, highlighting the need for robust evidence on environmental safety and system performance under cooler climatic conditions. A multiparameter assessment was conducted to compare the physicochemical and sanitary quality of reclaimed water with conventional irrigation sources and to evaluate temporal changes in soil properties, including macronutrients, physicochemical and microbiological indicators, as well as selected metals and their potential transfer to plant tissues. Plant performance was assessed using biomass production, developmental stage and photographic documentation. The results show that reclaimed water met key sanitary and chemical requirements and did not adversely affect soil quality or plant development. Observed exceedances of reference values in soils or plant tissues were primarily linked to initial soil conditions rather than to inputs associated with reclaimed-water irrigation. Differences between irrigation variants influenced nitrogen, phosphorus and potassium availability, however, no toxic concentrations were observed. Metal uptake by plants was generally low. Pb was the only analyzed metal that exceeded the adopted plant reference value in some irrigation variants; however, similar patterns were observed in both reclaimed-water and control treatments, suggesting an influence of background soil conditions. The findings support the potential role of water reuse in sustainable agriculture, contributing to circular-economy objectives and reduced freshwater demand.