The European Water Framework Directive (WFD) prescribes that all water bodies in Europe should achieve ‘good ecological status’ (GES). Maintaining a certain water flow is a pre-condition for the achievement of GES in areas of water scarcity. In such areas, reclaimed waste water is seen as a promising measure to keep river flow at a sufficient level. The contingent valuation method is applied here to estimate the non-market environmental benefits of using reclaimed water to maintain river flow levels in the Segura River Basin in south-eastern Spain. The assessment of the economic benefits of specific measures gives policy makers more information than a cost-effectiveness analysis alone, which is currently the most commonly used tool to assess potential measures under the WFD. The results show that the implementation of this measure produces significant non-market benefits that are larger than the investment and operational costs of reclaimed water treatment plants.