yes, you can bring all you want aboard. I would advise you to bring only a couple bottles of water and re-fill them on the ship. The extra weight and the bother isn't worth it. Water on the ships is very good or you can always buy more in port.
I brought 6 big bottles of water and replaced one of the bottles with peach schnapps. Unfortunately, one morning I decided to make a pot of coffee with my "water" and picked the wrong bottle. You should have smelled that coffee! It was pure peach schnapps!