The process of osmosis is defined through the explanation of “chemical potential” in a solution. The chemical potential of a solution is inversely affected by the concentration of salt, and directly affected by the temperature of the water and the pressure of the solution. If the solution has a constant temperature and pressure, and the salt concentration increases, then the chemical potential decreases. But if the temperature and/or pressure increases, then the chemical potential increases accordingly. The feed water for brackish water reverse osmosis systems generally has a higher chemical potential than the feed water for a sea water reverse osmosis system mostly because the salt concentration is lower.