Water is odourless and tasteless.
It has a bluish tint that can be seen in very deep layers. Water can remain a liquid even below its freezing point, up to -25 C, if it is not disturbed and if the temperature does not drop further and no particle or ice crystal is added to it. Water is used in the metric system to define the gram. Blood in animals and sap in plants is mostly water. The world average rainfall is 860 mm.