Hydrogen bonds and their fluctuations are one of the factors that determine the unique properties of water . Building models of formation and rupture of hydrogen bonds due to non-eigen vibrations of a molecule of water is to a large extent determined by the availability of accurate information on the geometric structure of the water molecule. Geometric parameters of the water molecule have been well studied for the gaseous state. This was aided by the possibility of an experimental study of the regularities in the rotational spectra of molecules. However, some questions about the geometry of the water molecule in the liquid state remain unanswered. For example, many sources state that the valence angle of the water molecule decreases during the transition into the liquid state . Based on the experimental data of molecular vibration spectra in D2O and H2O molecules , the authors have estimated valence angle of water in the liquid state. Consequently, the value of the valence angle of water in liquid state was determined to be (89 ±2)°. A question of determination of libration vibrations of water molecule, as well as the analysis of its consequent inversion doubling, based on the new information on the equilibrium angle of the water molecules in the liquid state, constitutes an interest and is discussed in the present paper.