Quoted from Carnival's website on Nov. 2, 2023:
"Carnival carries distilled water which can be purchased either pre-cruise if you are sailing from a US port, or once on board. For pre-purchase, please contact our Fun Shops department at 1-800-522-7648 ext. 70039, Monday-Sunday from 9:00am-9:00pm ET. For purchase on board, please contact Room Service. Should you wish to bring your own distilled water with you, it must be hand-carried along with your CPAP machine."