On average we drink between 2-4 litres of water a day. But it takes 1,500 litres to produce just 1 kg of grain and 10 times that quantity (15,000 litre) to produce 1 kg of meat.
To produce enough food to satisfy a person's daily need, it takes about 3,000 litres of water, or a thousand times more than the water we drink.
Today agriculture accounts for 70% of the total water use, followed by 20% for industry and energy, and about 10% for domestic use.
In 2007, the estimated number of undernourished people worldwide was 923 million.
Over the period up to 2050, the world's water will have to support agricultural systems that will feed and create livelihoods for an additional 2.7 billion people.
The extent of land under irrigation in the world is 277 million hectares, about 20% of all cropland.
Irrigation increases the yields of most crops by 100-400%, and irrigated agriculture currently contributes to 40% of the world's food production.
Poor drainage and irrigation practices have led to waterlogging and salinisation of approximately 10% of the world's irrigated lands.
The Intergovernmental Panel on Climate Change predicts that yields from rain-dependent agriculture could be down by 50% by 2020.
Due to climate change, Himalayan snow and ice, which provide huge amounts of water for agriculture in Asia, are expected to decline by 20% by 2030.
