Since it was never clarified about how long we cannot live without water for, then I shall do it myself. The resolution only states that we cannot live without water, but never states a specific time period. I shall choose a time period for this debate as a set up. "We can't live without water for 2 hours." I eat breakfast at 8:00 A.M and don't have any drinks until 12:00 A.M. That means I can live without water for at least a minimum of 4 hours. And since your resolution is "we can't live without water", you are applying "we" to everybody. If at least ONE person can live without water for 2 hours, which is me, then the resolution is then negated.