Again.... I would not bring a filter as the OP asked. That is NOT Necessary as a Brita filter nor any other filter will filter out anything more than a Triple RO system can filter out. That company that makes the "N" titled water, the "AF" water, the "D" water; companies do not go this as high of a filtration system. It is 3 times more filtered than any of the store brand water.... So, filtering Triple RO water is like taking your car through a "Detailed 2 hour car wash" then taking it through the $2 Car Wash at your local gas station. Did your $2 car wash just do a better job after your $85 car wash.... No, I think you just wasted $2..... Does that rambling make sense???
We, especially me, drink A LOT of water. It is very normal for me to down about 32 ounces with dinner alone... We usually use the ship's glasses on the ship and in the room. We actually do bring water bottles but they are aluminum ones, because we are very aware of the BPA in plastic water bottles. The bottles we use are just taken off of the ship. We fill them with the ship's water and clip them on to our belts and take them off the ship. Some people bring bottled water just for this reason.
Do know.... You can let your SRH know that you drink a lot of water and they will bring it to you. We have Room Service bring a pitcher of ice water in the morning, we have our SRH bring one at morning service and our SRH to bring one at turn down service. We ask for fresh glasses twice a day from our SRH and you get a card to ask when do you want ice delivered. We choose AM & PM and our SRH brings our pitcher, our ice bucket and glasses twice a day. We also have water in the DR....
So I hope that helps a bit!