I did it today. Admittedly I was a bit desparate, but I did it. The setting: I am in Parque Rodo (a nice neighborhood outside of the city center) at my tutor's apartment/school. It was 5PM, and I had just sat down at the table to begin going over how the weekend was blah blah blah. Then it hit me: I had forgotten to drink water the whole day, and actually hadn't eaten that much either - I was light headed and couldn't focus on the lesson.
"Juan, could I ask you for a glass of water? I am dying of thirst." But when the water came to me, I immediately realized that this was not bottled "safe" water...this was the real thing. I took a few sips (for the lesson's sake so I could concentrate), then continued on with Juan. About a minute later I looked over to the glass and noticed DNA type strands floating around in the glass - and not just a few of them.
Well, sooner or later I needed to accustom my system with the bacteria down here - might as well have been today...the seventh day of my stay.