The European Water Framework Directive (EWFD) demands a detailed analysis to determine which changes and measures within the surface water system are required, which actors require detailed scrutiny, and which technology has to be developed in order to guarantee that the quality of the surface water is complying with this Directive. This paper will discuss a holistic model developed for the optimization of the surface water system for a water authority in The Netherlands, which is influenced by (i) waste water streams originating from e.g. households, industry, agricultural and transport activities among others and (ii) the end-of-pipe technology of waste water treatment plants, while interfacing with (iii) thermal treatment and minerals and metallurgical processing for the recovery of specific elements from waste water sludge and other residues created during waste water treatment. The paper develops a fundamental basis that can feed factual information such as optimal combination of measures (technology and policy) into sustainability frameworks or the implementation of the EWFD. This optimization is affected by quality constraints, costs, energy, environment and interactions between the various materials present in the different streams in the water system. By incorporating these parameters into the model a tool is provided that provides metrics to measure the 'sustainability' of the Web of Water (WoW), while linking to and harmonising with the Web of Materials/Metals (WoM). The WoW optimization model links material cycles from e.g. food, transport, agriculture and industry to the recovery of materials from the water cycle with the pyrometallurgical and thermal processing of minerals/materials, hence quantifying resource conservation and sustainability on the interface between aquatic and product manufacturing systems and the process industries. (C) 2009 Elsevier Ltd. All rights reserved.