Keep in mind that all drinking water that's available on a cruise ship is required to go through a strict testing system. Even though ocean water is filtered before any passengers drink it, the B12 and D3 vitamins that can naturally be found in ocean water still remain.

Yes, modern cruise ships are marvels of maritime engineering that generate the vast majority of their fresh water directly from the sea. They primarily use two methods: Reverse Osmosis (RO) and Multi-Stage Flash Distillation. Reverse osmosis involves pushing seawater through extremely fine semi-permeable membranes at high pressure to remove salt, minerals, and bacteria. The distillation method uses the heat from the ship's massive engines to boil the seawater, then captures and condenses the steam into pure water. In 2026, a large cruise ship can produce over 500,000 gallons of fresh water per day. Once the salt is removed, the water is mineralized for taste and chlorinated to meet strict World Health Organization and U.S. Public Health standards. This water is used for everything from the swimming pools and showers to the ice in your cocktails. By filtering their own water, ships avoid the need to carry massive, heavy water tanks, which improves fuel efficiency. Furthermore, modern "Advanced Wastewater Treatment" systems ensure that any water discharged back into the ocean is often cleaner than the surrounding sea water, meeting the highest environmental regulations.