The European project for the sustainable use of water in industry. As part of the "AquaFit4use" joint research project, research was undertaken into the recycling of wastewater flows and partial process water flows in various water-intensive industrial production contexts, such as the paper industry, but also the food and textile industries. Cross-industry process chains for recycling water were devised and new water technology solutions were developed. The key priority was the reliability of the processes involved, taking account of the cost situations in the sectors concerned. Tasks included intensive laboratory studies into selected recycling technologies, as well as verification of the processes involved and optimisation on a pilot scale.