So much water is now being used that ground water levels in Helmand are estimated to be falling by 3m a year.
The fear is that pretty soon the water will simply run out.
"Maybe this boom will not last longer than 10 years," says Orzala Nemat, who runs the Afghanistan Research and Evaluation Unit, the country's biggest think tank.
That won't just affect the people who have moved into the desert areas, she says. It will affect the entire region.
