"'We will need 0.6 gallons of water to grow one head of lettuce in this process,' says Adams. 'In California and Arizona, where most lettuce in the U.S. comes f

"'We will need 0.6 gallons of water to grow one head of lettuce in this process,' says Adams. 'In California and Arizona, where most lettuce in the U.S. comes from, it takes 365 gallons of water to grow a single head.'"