Yes.
Don't order that much water!
1 gallon per person per day is a good starting point, but if you're going to be on any of the larger islands, water will be available. We ordered all the water last time too and were tripping over it most of the trip AND had many gallons left over.
Order for 1/2 the trip, see how much you actually use, then buy more if need be. That's what we're doing this trip.