Subcritical water (SubCW) is a term commonly used for water heated under pressure from its atmospheric boiling temperature (100 C) to its supercritical point (374 C). At these conditions the thermal motion of water molecules increases, markedly changing its properties. Unlike ambient water, the highly hydrogen-bonded structure at subcritical conditions slowly starts to dissipate, resulting in a decrease of permittivity (polarity), increase of diffusion rate and a decrease in viscosity and surface tension (Smith, 2002).