"Bonci suggests that body weight may be a better gauge. "Take a third of your weight in pounds and that's how many ounces you need to drink daily," she says. A 150-pound woman, for example, will need 50 ounces, which translates to a little more than six cups of water."
So to need only 7.8 ounces, you would weigh 23.4 pounds, SoCalMinew? Or did you mean cups?
Am I missing something here?