My advice would be bring your own water onboard. I drink alot during the day (water that is) and at $3-$6, it gets to be expensive. In saying that, I do think that the water on ships has gotten alot better.
Mariner-05/06 & 10/09
Oasis Inaugural Cruise-12/09
Monarch-03/10 & 07/10
Mariner; RSS- 10/12
Booked:Celebrity Infinity, 05/15/2015