They'd use "Medusa bags" (named after the jellyfish, not the gorgon-pay no attention to the strongly negative associations). The biggest Medusa bags are longer than seven football fields and hold 1.5 billion liters of water.
The companies that set up these schemes sometimes stand to make significant profits by selling water at a premium in parched locales. As one such enterprising businessman, Ric Davidge, said, "I am confident that the price of water will continue to move in our favor."
We're worried that if the free market has the last word on who gets water in the coming years, that'll leave a lot of poor people thirsty (or dead).