Chemists at the University of Utah have discovered that the absolute minimum temperature at which water can stay liquid is - 48 degrees Celsius (-55 F). At this temperature, the molecular structure of supercooled water changes physically to form tetrahedral, with each water molecule loosely bonded to four others, according to a study by Valeria Molinero and Emily Moore. "This intermediate ice has a structure between the full structure of ice and the structure of the liquid,” she adds. “We’re solving a very old puzzle of what is going on in deeply supercooled water."