If you must take water and if you must fly then you must pack it in your checked baggage.
Rather than that I would:
1. Just bring a couple of refillable bottles and use the ship's water. The "cruise legend" that ship's water is high in sodium is just that. A cruise legend. Softened water has much higher amounts of sodium in it.
2. If you still need to bring water I would take a taxi from the airport and then have the taxi stop at a grocery store and grab some water there. You will be allowed to bring 12 bottles per person on board.