Water Potential Ψ

The water potential Ψ is the pressure created by water molecules.Under standard conditions of temperature and pressure (25°C, 100kPa), pure water has a water potential of zero.The addition of a solute to pure water lowers the water potential i.e. makes it more negative.An increase in pressure increases the water potential.Water potential is expressed as the potential energy of water per unit volume relative to pure water.It quantifies the tendency of water to move from one area to another due to osmosis, gravity or mechanical pressure and other effects.Water potential is typically expressed as potential energy per unit volume.Water will move from an area of higher water potential to an area of lower water potential until an equilibrium is established.