What is the SG of water?

The specific gravity (SG) of water is a dimensionless quantity that is defined as the ratio of the density of water to the density of a reference substance, typically water itself at 4°C, where it has its maximum density of approximately 1,000 kg/m³. Therefore, the specific gravity of water is 1.0. This means that water has the same density as itself, which serves as the baseline for comparing the densities of other substances.