Under 15 Min. Under 15-45 Min. Survival in cold water depends on many factors. The temperature of the water is only one. Others include body size, fat, and activity in the water to name a few.
Large people cool slower than small people.
Fat people cool slower than thin people. Children, because they are small, cool faster than adults. By swimming or treading water, a person will cool about 35 percent faster than if remaining still. Because the head is an area of high heat loss, drownproofing will cause a person to cool about 80 percent faster than if he kept his head out of the water. Drownproofing thus reduces survival time by nearly one half in cold water.