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I'm not sure because I have always been assured that the water throughout the ship was potable. Let's face it if Americans drink gallon's of it, it's going to be very safe they never take an hygienic risk and I have spent in excess of 700 days at sea and never had any ill effect at any time apart from a cold.......Nei.
I would always suggest that with any water that you are not used to drinking air caution. I understand where your coming from and yes it is very pure but if your body is not used to that kind of filteration and mineral content it MAY no agree with you.