A concentrated solution and a dilute solution are placed on opposite sides of a container, separated by a semipermeable membrane. Water from the dilute solution will naturally pass through the semipermeable membrane and permeate into the concentrated solution side. The liquid level on the concentrated solution side will rise higher than that on the dilute solution side, creating a height difference. This naturally generates a pressure difference until the liquid levels on both sides reach equilibrium. We call this pressure osmotic pressure.If an additional pressure is applied to the concentrated solution side, the water from the concentrated solution will then permeate in the reverse direction through the semipermeable membrane toward the dilute solution side. This process is called reverse osmosis. This technology is commonly used in water treatment equipment.