Penny, some people actually use their CPAP during the flight, especially overnight flights, so waiting until they arrive isn’t an option. But I’ve researched this and everything I’ve read says you’re correct that using bottled water is fine as long as you clean the machine afterward. Even if you have to do it for a few weeks, as you might for a multi-stop vacation abroad. The concern is about mineral buildup. If a person is worried about bacteria, there are battery-powered disinfecting wands available in camping stores that will kill any bugs in a bottle of water with a couple of stirs.