  We develop a series of approximations to calculate free energy of a polar
liquid. We show that long range nature of dipole interactions between the
molecules leads to para-electric state instability at low temperatures and to a
second-order phase transition. We establish the transition temperature, T_{c},
both within mean field and ring diagrams approximation and show that the
ferro-electric transition may play an important role explaining a number of
peculiar properties of supercooled water, such as weak singularity of
dielectric constant as well as to a large extent anomalous density behavior.
Finally we discuss the role of fluctuations, shorter range forces and establish
connections with phenomenological models of polar liquids.
