How do cruise liners get, and keep, fresh water on board – eg for drinking? Cruise ships are of course, surrounded by water, but it needs to be made suitable for use by the passengers, so all ships have desalination systems on-board, which remove salt and impurities and turn it into fresh water.

While the vast majority of modern cruise ships in 2026 use advanced desalination systems, not every single ship relies on them exclusively. Large, contemporary vessels typically feature sophisticated reverse osmosis (RO) plants and multi-stage flash evaporators that convert seawater into high-quality potable water, often producing over 500,000 gallons daily. However, smaller or much older river ships and coastal cruisers may lack the space for such plants. Instead, these ships "bunker" (load) fresh water from municipal supplies at various ports of call. Even for mega-ships, desalination can be restricted by environmental laws or water depth; they cannot operate RO units in shallow or highly polluted waters to avoid membrane damage. Therefore, while most "mainline" ocean cruises desalinate their own water for sustainability, the industry still utilizes a hybrid approach involving port-side loading to ensure a constant, safe supply.