This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and USS38,221 for America and Europe, respectively. (C) 2009 Elsevier Ltd. All rights reserved.