First, only 2.5% of the water on earth is freshwater. Second, most of freshwater not locked up in ice caps or glaciers comes at the wrong time and place - in monsoons and floods - and 20% is in areas too remote for humans to access. Although 60% of the world’s population lives in Asia, the continent has only 36% of the world’s water resources (Table B.2). These two types of freshwater vary in a number of key characteristics and these differences have direct implications for water security. Groundwater constitutes nearly 90% of the freshwater on our planet (discounting that in the polar ice caps), but only a small proportion (less than 5%) can be withdrawn each year without depleting the resource base.