At room temperature, 16 U.S. fluid ounces of water weighs 1.04 pounds. While there is a well-known saying about water that says that "a pint's a pound the whole world round," and 16 ounces equals 1 pint, the weight of that pint is not always precisely 1 pound.
The density and specific gravity of water varies depending on the temperature of the water. At 32 degrees Fahrenheit, when water is cold enough to freeze, the specific weight of the water is 8.34 pounds per gallon, so 16 ounces of water weighs 1.05 pounds. When the water reaches its 212 F boiling point, its specific weight goes down to 8 pounds per gallon, so the weight of 16 ounces is 1 pound.