A survey of wastewater characteristics in Europe has been conducted to evaluate the range of pollution ratios (BOD5/COD, SS/COD, N/COD and P/COD) that can be used to assess the robustness of wastewater management systems in terms of sustainability. Data were collected from questionnaires sent to wastewater treatment plants managers (Austria, France), from national data bases (Denmark, Flanders, The Netherlands), from national contacts and from literature. Average values are proposed for N/COD (/ 0.1 mg/mg), P/COD (/ 0.016 mg/mg), SS/COD (/ 0.5 mg/mg) and BOD5/COD (/ 0.4 mg/mg). But these values are subject to timevariations (short and long-term range) which merit further investigations.