In our universe, the three most common atoms are Hydrogen, Helium and then Oxygen. Carbon is number four. In terms of the most common reactive elements in the universe, hydrogen is number one and oxygen is number two. This is why water is so common. H2 + O2---->H2O is the main chemical reaction of the universe. Water or H2O is also the second most common molecule in the universe behind only hydrogen gas or H2.
Water is the most common solid material in the universe; ice. Ice is responsible for second generation star formation. Water has the unique characteristic of expanding when freezing and contracting when melting. Almost all other natural materials do the opposite.
In terms of star formation, as solid ice and other materials collect due to gravity, the pressures built. This heats and pressurizes the ice, which melts and lowers it volume by about 10%. This results in a sudden escalating collapse of the star precursor, that can create an affect called fusion hammer, which lights the star. Water, as heavy water, contains the hydrogen used for fusion.
Water is the most studied substance in all science. There are more scientific papers on water than on any other substance. Water is in a class all by itself with exceptional properties when compared with other materials. The 74 anomalous properties of water are those where the behavior of liquid water is entirely different from what is found with other liquids. For example, water is the only common material found as ice, liquid and gas, at the same time, at the conditions of earth.
Water is critical to life. There is no substitute. If we dehydrate a cell, nothing will work. If we substitute any other solvent, still nothing works properly and there is no life. If we add water, everything now works and life appears again. Water provides a very unique nano environment, in which organic life was able to evolve. Water makes use of its many unique and anomalous properties to induce inert organic compounds into the animated building blocks needed for life.