  Glass-to-glass and liquid-to-liquid phase transitions were observed many
years ago in bulk and confined water with or without applied pressure. It is
shown that they result from the competition of two-liquid phases separated by
an enthalpy difference depending on temperature. The model is based on the
classical nucleation equation of these phases completed by this enthalpy saving
existing at all temperatures and a pressure contribution. The thermodynamic
parameters of amorphous water, the multiple glass transition temperatures, the
enthalpy changes, and the temperature of maximum density under negative
pressure above Tg =227.5K are predicted to be in agreement with many
measurements
