Ships are supplied with water from various sources: directly from the public utility system at the port, from water supply vessels or barges, bottled water, ice or, if water production on board is possible,through processes such as desalination and reverse osmosis. All elements of a ship's water supply chain are exposed to the influence of different factors that may have a negative impact on water safety on board or on human health. Potable water standards are the same for vessels and for land-based facilities. In recognition of the importance of drinking water and the impact it can have on human health, stringent quality standards have been laid down in national and global regulations. The aim of the study was to describe the water supply system on ships and its weak points, as well as the health risks that the use of npolluted drinking water can entail. The Medline Database has been searched using the following key words: ship, water supply, waterborne infections. Other available literature has also been used, as well as national and international regulations on drinking-water safety. Drinking water on ships is managed in line with the hygienic and health standards applied along the entire supply chain, from the source to the point of consumption. Regardless of the sanitary control system used by the authorised institutions on the ground, ship officers must oversee the entire water supply and distribution system on board, as well the water production systems if these exist. That means that they must be well aware of all of the fundamental facts of the supervision system, as well as the weaknesses of the water supply system. Maritime studies students, future deck officers and engine officers, must all receive training on the weak points of the system and on water contamination prevention.