| Water is the primary medium through which climate change impacts the earth's ecosystem and people. Climate change is the fundamental driver of change in the world's water resources and adds additional stress through its effects on other externalities. The UN suggests that each person needs 20-50 liters of water a day to ensure their basic needs for drinking, cooking and cleaning. The world uses fresh water about 70 percent for irrigation, about 22 percent for industry and about 8 percent for domestic use. Another general perception of water quality is that of a simple property that tells whether water is polluted or not. In fact, water quality is a complex subject, in part because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial and commercial activities (e.g. manufacturing, mining, construction, transport) are a major cause of water pollution as are runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage. |