Several ways to handle—you can call Princess and they will note for you—also it can be handled online under Check-in status and go to dietary request and click distilled water for CPAP—however I have found both of these methods being a 50% chance of room steward actually being made aware—frankly it is just not a problem you can ask room steward and he/she will bring you a full container first day—they will even bring an extension cord for machine if need be though a fellow cruisecritic follower turned me on to using alternative outlet behind bed to forego the need for any extensive cord—he will no doubt read this thread and offer up his sage advice again