clutchargo, The water will not get you sick and the taste of the water will vary according to where it comes from and your location. In the city you have the city water supply which comes from a main RO plant through pipes to your resort. Other areas use cisterns to catch rain water and/or RO's to make water. The over all quality of water on the Island is good. If the taste does not agreee with you, bottled water is available and is relatively cheap. You do not have to fear the water and I drink from the tap all the time.
Water technogy has come a long way at vacation destinations in most the Western Hemisphere, at least, and is no longer the problem it once was. It doesn't hurt to ask the question though. And drink the bottle water if you prefer but there really is no need to use bottle water to brush your teeth; wash dishes or anything like that.
Have a good stay.
Somewhere on a beach in Belize