Water chemical formula H2O is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance that is the main constituent of Earth. hydrosphere and the fluids of all known living organisms in which it acts as a solvent. It is vital for all known forms of life. Even though it provides no calories or organic nutrients. Its chemical formula H2O indicates that each of its molecules contains one oxygen and two hydrogen atoms connected by covalent bonds. The hydrogen atoms are