Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane to remove larger particles from drinking water.

In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential a thermodynamic
parameter. Reverse osmosis can remove many types of molecules and ions from solutions, including bacteria, and is used in both industrial processes and
the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass
to the other side. To be "selective", this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller
components of the solution (such as the solvent) to pass freely.