Seawater - Wikipedia

Although it is clear that a human cannot survive on seawater alone, some people claim that one can drink up to two cups a day, mixed with fresh water in a 2:3 ratio, without ill effect. The French physician Alain Bombard survived an ocean crossing in a small Zodiak rubber boat using mainly raw fish meat which contains about 40 percent water (like most living tissues), also small amounts of seawater and other provisions harvested from the ocean. Naturally, the veracity of his findings was challenged but an alternative explanation to Bombard's survival was not given. His message was that humans can survive at sea on the water content in fishes. InKon-Tiki, Thor Heyerdahl reported drinking seawater mixed with fresh in a 40/60% ratio. A few years later another adventurer namedWilliam Willis claimed to have drunk two cups of seawater and one cup of fresh per day for 70 days without ill effect when he lost part of his water supply.^[12]