Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless,[c] and nearly colorless chemical substance, and it is the main constituent of Earth's hydrosphere and the fluids of all known living organisms Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless,[c] and nearly colorless chemical substance, and it is the main constituent of Earth's hydrosphere and the fluids of all known living organisms Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless,[c] and nearly colorless chemical substance, and it is the main constituent of Earth's hydrosphere and the fluids of all known living organisms