I would say a good couple of weeks, or just over a month.
One widely circulated concept to help set priorities is called the "Rule of Three": Employed a mnemonic device, the Rule of Three states:
1. Humans cannot survive more than three hours exposed to extremely low temperatures.
2. Humans cannot survive more than three days without water.
3. Humans cannot survive more than three weeks without food. (remember the case in Florida that was so controversial?)
Since Coke, though not straight water, your body can use the liquid and hydrate yourself.
So, I'll say about a month and one dollar.