A vibrational analysis of liquid water is reported, assuming a completely hydrogen-bonded network with continuously varying strengths of the hydrogen bonds. Frequency distribution calculations are made for intramolecular stretching and bending modes and for the intermolecular frequency region. The calculated distributions are compared with the experimental spectroscopic ones. As another test vapor pressure isotope effects are calculated from the theoretical distributions for some isotopic water molecules. Results are compared with ones of other authors obtained from a mixture model.