re..How do you know if you have sleep apnea?
Many symptoms listed with a quick google search. To confirm---You can get a "recording pulse oximeter" for 50-150 bucks. It will record your oxygen level as you sleep. Try it for a couple nights and see if you notice a "sawtooth wave" where your oxygen level ramps down over a 30-45 second period and then jumps rapidly upward when you finally gasp for a breath. IF you have an issue, you'll be convinced of it (and the magnitude) before you stick your toe in the water with your doc and the FAA.

re..carrying distilled water.
My brother has been using CPAP for over 15 years. He uses tap water. Think about it. Tap water is distilled water with some extra minerals in it (unless you're in Flint, Michigan or something). In the morning, you have a slightly higher concentration of minerals in the water that's left in your machine. Dump that out, rinse it and use new water the next night. Or, drag around bottles of water and explain whazzup with that to every TSA guy you encounter. As previously mentioned, you can clean it out much easier than you can carry the bottles of water.

re..Z2 noise/roughness. Recommend turning their pressure relief feature to the lowest value. Lose the inline muffler thing that comes with it, saving some packing space as well. Put machine below the level of the bed behind a (noise absorbing) pillow. Go to amazon and get a "travelhose" collapsible CPAP hose, makes it much quieter.

Hope some of that helps.

CCN