as mentioned, don't even think about drink the so called potable water on an aircraft
In third world countries also ensure you break the seal on your water bottle (or you see the persons break the seal) Thrust me, I have seen the "recycling" that goes on.
Worse case of food posioning I ever got (and I travel a lot) was Business class lounge in New Delhi. I believe it must have been free orange juice they must have added local water to. One week of local vegetarian food, only drink beer from cans etc etc no delhi belly and then India gets me just as I leave
been back a few times since and no probs.