India's water resources

Water covers about 71 per cent of the earth's surface, but freshwater is only about 3 per cent of all water.

India has 2.45 per cent of the world's area and about 4 per cent of its water, but more than 17 per cent of its people. So water per person is limited.

India's water budget, in cubic kilometres a year:

• precipitation (rain and snow): about 4,000;
• river flow: 1,869;
• usable surface water: about 690, because of the terrain and uneven rainfall;
• replenishable groundwater: about 432;
• total utilisable water: 1,122.

Water is unevenly spread too: the Ganga, Brahmaputra and Barak basins hold about 60 per cent of the surface water, on about a third of the country's area.

In short: India has much water, but little of it is usable.