It is predicted that water at ambient conditions should undergo a phase transition to a dense phase of H₂O at a transition value Π_t of the local electrostriction pressure. The transition is accompanied by a latent heat as well as discontinuity in entropy and electric field. The values of the field in which recent X-ray scattering at a charged RuO₂/water interface revealed phase transitions to very dense ordered H₂O layers are met without adjustable parameters. The latent heat has been observed earlier at a Hg/aqueous electrolyte interface. An attempt at an explanation of the hydration of Sr²⁺ ions is undertaken.