What is the specific gravity of water?

The specific gravity of water is defined as a dimensionless quantity that represents the ratio of the density of a substance to the density of a reference substance, typically water for liquids and air for gases. Since the density of pure water at standard temperature and pressure (4 degrees Celsius) is set as 1 gram per cubic centimeter (g/cm³), the specific gravity of water is thus defined as 1.000.

This means that when comparing the density of water to itself, the ratio will always equal one because both are the same. The specific gravity is a useful reference point in various scientific calculations and helps in assessments of other substances by comparing their densities to that of water.

The other values listed do not accurately represent the specific gravity of water. Specific gravities less than or greater than 1.000 would indicate that the substance is either less dense than water or denser than water, respectively, which does not apply to water itself.