It’s always good to take your own water bottle so you can fill it up with the ships free juice drinks but just make sure the staff don’t see you doing it! The bottle can also be used when outside in the hot ports of call.
I think so many people do it now that the crew members have given up trying to stop them! Also I know on Carnival ships passengers are given the chance to purchase bottles of water before going off the gangway but they have to pay for it.
I agree. I have never seen anyone get in trouble for filling up water bottles. Here is another great tip: book your cruise with agencies. The good ones will be able to hook you up with extra onboard credits or amazing amenities to absorbs some of the beverage costs.