A man who ingests ample water but not food can, according to Ivy,1 survive twenty to thirty days, provided he is not subjected to physical strain to which fasting renders him unduly susceptible. The maximum time of survival of a person completely deprived of water rarely exceeds ten to fourteen days, even under the most favorable circumstances. The maximum recorded period of survival at sea without water is eleven days. When the daily intake of water is limited to less than 500 cc., the ingestion of a relatively small amount of carbohydrate and fat will maintain an otherwise starving person in better condition than if this food was replaced with an equivalent weight of water. Under certain conditions of shipwreck the person is likely to die in a short time from exposure to cold. In such cases food might be of more importance than water in prolonging life.
A TABLET EMERGENCY RATION FOR LIFEBOATS AND RAFTS. JAMA. 1944;125(7):494. doi:10.1001/jama.1944.02850250034011