However, researchers say countries in savannah regions, such as sub-Saharan Africa, could reduce their water requirement through better water policies and more efficient irrigation techniques.
One of the MDGs is to halve the proportion of people who suffer from hunger between 1990 and 2015.
Johan Rockström, from the Stockholm Environment Institute, Sweden, and colleagues analysed water requirements for food production in 92 developing countries ― including India, Kenya and Nigeria ― using data from the UN Food and Agriculture Organization.
The study found that to meet food demands, the rate of cropland expansion would have to continue at a similar rate to the past 50 years ― around 0.8 per cent each year. The expansion of agricultural land is a major cause of damage to natural ecosystems.
The authors say that to meet the MDG target, 50 per cent more fresh water ― an additional 2,200 cubic kilometres per year ― must be used for food production than at present.
And if water production is not managed more efficiently ― with measures such as better use of local rains and more efficient measures in water productivity in rain-fed and irrigated agriculture ― the amount required will double by 2050, which the authors say would cause further degradation of ecosystems.
Hassan Moawad Abdel Al, former president of Alexandria's Mubarak City for Scientific Research and Technology Applications welcomed the report, saying it "identified the problem as well as the solution and put the ball in the playground of African countries to act".
Abdel Al called for an African observatory to monitor food and water production and identify relevant technologies and policies.
He said this would encourage networking amongst African water scientists, biotechnologists and policy makers, and raise awareness about the role of water in food production and hunger eradication, as well as stepping up regional co-operation in water management.
While agreeing with the conclusions of the report, Seleshi Bekele of the International Water Management Institute in Ethiopia pointed out that water saving technologies are generally not accessible or affordable to local rural communities in sub-Saharan Africa.
He called for investment to "access, control and improve the management of the water".
The study was published online in Proceedings of the National Academy of Sciences.
Reference: Proceedings of the National Academy of Sciences 104, 6253 (2007)