Why is water potential of pure water zero?

is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to , gravity, mechanical pressure, or matrix effects such as surface tension. Water potential has proved especially useful in understanding water movement within plants, animals, and soil. Water potential is typically expressed in potential energy per unit volume and very often is represented by the Greek letter Ψ.

Water potential is always negative, water being pure has a potential of zero as it can diffuse the easiest. The higher the concentration the more negative the water potential.