In recent years, the international community has paid attention to the water quality problem, especially since Agenda 21, which is the action plan to protect the environment, was adopted in 1992 (WHO/UNEP 1997: ). In addition, in the United Nations Millennium Development Goals, one of the goals is to ‘reduce by half the proportion of people without sustainable access to safe drinking water’ (United Nations 2000). It has been internationally acknowledged that water problems are at a crisis point for human life as well as the environment. Along this line of growing international concern, this paper.
