What is the density of water at 26 degrees Celsius?

Answer 1

According to the table of measurements given by Wikipedia, water under standard pressure (1 atmosphere) at 25oC has a density of approx. 997.05 kg/m3 and at 30oC decreases to approx. 995.65 kg/m3, so linear interpolation suggests the density at 26oC is approx. 996.77 kg/m3. However, the density of water with respect to both pressure and temperature is known to be both nonlinear and non-monotonic; for example, the maximum density of water is found at approx. 4oC instead of 0oC, which is why ice floats in a glass of water. The density of seawater is also affected by salinity, in addition to freshwater impacts of pressure and temperature. The full range of water density produces complex diagrams, and it's presence on the Earth in all physical forms (phases) makes water one of the most studied substances in science.

Answer 2

The density of water at 26 degrees celcius = 0.99678 g/mL.

Reference: CRC Handbook of Chemistry and Physics, 55th ed. (See page F-4, Volume properties of water, at 1 atm.)