I've been to both Mexico and India many times. They are very similar in terms of their water sanitation (basically is none). I wouldn't drink the water if I was in the desert. Like all humans, their systems just adapt.
To give you an example, while vacationing in Cabo, I ate some of their fantastic authentic mexican food in a small town restaurant. They put a lime on my Corona that had been washed with tap water. They call it Montezuma's Revenge, and it just wreaks havoc on your digestive system.
In any case, Costco is selling an undersink RO system, so I guess I'll just use my dockside filter, and then RO the galley water, wilst also shocking the tanks with bleach.
Any other thoughts?