Cancun Trip

Me

Next month we've planned a family vacay to cancun... our little guy will be 6 months old. My question is, how would we take all the necessary water he would need for the whole week we're there? I only give him distilled water with his formula & I don't if I would be able to find any supermarkets out there that would be safe to go to. Anyone experience taking a few gallons of water past the TSA for carry on?