Need to purigy water?
Have been different places in the Caribe. Roadtown, Tortola has excellent drinking water. They use reverse osmosis. St. Lucia is okay, you can drink it. Would not touch the water from St. Thomas, USVI!
On the other hand, if you are worried, with the AquaPur system I have drunk, cooked with, made coffee with, brushed teeth and showered with water from the Hudson River. Happened one year when we were delivering a boat down from the Erie Canal system late in the year (October). We got to Tarrytown Marina and the marina was closed. Refused to let us run a hose. The restaurant we ate at even refused to let us take a pitcher of water to the boat to fill up the coffeemaker! So, we hooked up the watermaker, and when the tank was full, did the test with the little tablets and it turned out to be even more pure than a cup of water I had gotten to go (for 2.00) from the restaurant!
In any case, the AquaPur watermakers do work wonderfully. This was one that was a portable model - you could link it to the water system or use it independently in a life raft. (If they can make the Hudson drinkable, what more could you ask?) And, from my experience in the BVI and the Grenadines, water is the least you need to worry about.
Best of luck,