All these anecdotes about foreign stuff in the water would apply to your municipal water supply too...you just don't get to see what's down there. Dilution is the solution...you don't need pure water, you just need for the concentration of bad stuff (ie decomposing frog) to be low enough not to hurt you. Problem with airplane tanks is that they're small, so anything that gets in there will have a high concentration.

I avoid drinking it, but if I need coffee, oh well. The water probably isn't as bad for your health as a diet soda.