The reuse of effluents, brines and sludges in agriculture can be a sustainable way to reuse residual streams of water, but the reuse has the potential to result in environmental and food chain accumulation of contaminants. The potential risks of residual streams of water will be indicated by researching the bio-availability/accessibility, chemical transport of the contaminant in the soil and water of different soil compartments and by relating the values to quality standards. For a broader spectrum of the reuse opportunities of residual water streams the Netherlands and Qatar will be addressed as case studies. From the boarder spectrum a sustainability tool can be developed to assess the sustainable reuse of residual water streams.