Wastewater reuse is a common occurrence in0 most basins as treatment plants discharge their effluents into fluvial courses that are once collected downstream. This is called unplanned reuse.

In 2009, the Water Reuse Program in Catalonia (PRAC) was published, which defined a series of proposals for management and investment in reuse. Although the potential of regenerated water to improve water availability in Catalonia is widely recognized in all published studies, there are still many barriers that limit its application.