I always advise against drinking the tank water unless it's your personal boat and you know the history of the tanks. Water comes in 6 gallon cases. I would get 4 cases to start and refill along the way. I can't impress enough how important it is to stay hydrated so be sure to purchase more as you go along. There used to be refill spots along the way but I don't have a complete list of locations. I think there is still a refill machine at Anegada Reef Hotel.

We usually order 2 or 3 small bottles and a 1.5liter bottle for each person and refill from the gallon jugs.