I was in Rio at a fairly upscale hotel. The clerk spoke perfect English and asked me if I’d ever been to Rio before. When I said no, he went over how important it was to never drink the tap water. He also went as far to say that I should use the complementary bottled water to rinse my mouth out when brushing my teeth. Also he warned when I order drinks don’t get drinks with ice in them! Beer was the safest bet. Only the locals have the constitution to handle the water in Rio and only small amounts at a time.
In preparation for my first visit to Africa many years ago I consulted with an Infectious Disease specialist that I knew who was on the staff of the hospital where I was working at the time.He gave me that very same advice as well as many other bits of advice.As a result we were brushing our teeth with orange soda (which was widely available for some reason) for my entire trip.
Maybe I'm being overly cautious about Brazilian aircraft...who knows!