An understanding of the interaction between urban systems and the environment is crucial for water management. In this thesis, water balances are developed based on different software tools and the results are compared. In addition, a balance of waterborne copper (Cu) is established in order to link the flow of water with the flows and stocks of a substance in an exemplary way. The goals of this thesis are I) the identification and quantification of sources, pathways and sinks of water and Cu in Vienna, II) the use of these results to develop pollution control measures particularly for Cu, and III) a comparison of the software tools applied. Water and Cu balances were established for 2008 in two steps based on the software tools UVQ and STAN. The first step consisted of a rough simulation of the water balance to evaluate whether outcomes are promising or not. Results of these first simulations were used to provide a framework for the second step, where both models have been improved. Finally, a generic STAN model was developed to establish both water and Cu balances. Due to the fundamental differences of UVQ and STAN, the findings of these two tools vary, especially for Cu. Each tool proved to have its advantages and disadvantages. Results indicate that in Vienna, 84 % of waste water is directed to the central treatment plant and 15 % is lost via combined sewer overflows. In addition, 70 % of runoff generated by rainfall reaches the sewage treatment plant, which is more than required by the relevant directives proposing 40 to 60 %. Private households and industry are major waste water producers. In total, 66 % of Cu flows are controlled, and 34 are emitted to the environment without control (24 % to atmosphere, 10 % to surface waters via overflow). The major Cu import (48 %) originates from consumer products of private households, of industry, tourism and trade. Despite a lack of data, the application of the models yielded plausible and useful results.