Investing in the infrastructure and knowledge to manage water systems will help the world cope with water scarcity, says David Molden, deputy director of the International Water Management Institute.

Up to twice as much water will soon be needed to support the world's growing population. We must learn how to live with less water by making better use of what we have, says Molden.

Agriculture in the developing world is already using tools to produce more food with less water. Farmers in India and Nepal use low-cost drip irrigation. In Sub-Saharan Africa, improved crop varieties, fertiliser and soil management are helping conserve water. And in Asia, "wet and dry" irrigation is replacing traditional constant flooding of rice fields

But 50 per cent of food — and therefore 50 per cent of water — is still wasted when it leaves farmers' fields. And many areas still suffer from salinity problems, dried up rivers and low water tables.

The problem is a lack of investment, says Molden and action is urgently needed. He recommends establishing incentives for farmers to better manage water supplies, supporting local actions, and investing in water management infrastructure.