Reverse Osmosis (RO) is a water purification process that uses a partially permeable membrane to filter out impurities from drinking water. During the RO process, pressure is applied to overcome the osmotic pressure, a colligative property driven by the chemical potential difference of the solvent, which is a thermodynamic parameter. The result is that solutes are retained on the pressurized side of the membrane, while pure water is allowed to pass through the other side. In order to be "selective", such a membrane should not allow large molecules or ions to pass through the pores, but should allow the filtered clean water to pass freely.

All RO systems will produce concentrated water to discharge impurities. Compared to traditional RO water purifiers, Glacierfresh Reverse osmosis system produces less concentrated water and saves 300% more water. You can collect concentrated water to mop the floor, wash your car, do laundry, etc.

Reverse osmosis water purifiers rely on semi-permeable membranes to filter impurities from drinking water. When tap water passes through the RO membrane, purified water and wastewater are produced. The ratio of purified water to wastewater is called the wastewater ratio. A 1:1 wastewater ratio means that 1 gallon of water is wasted for every 1 gallon of water purified, while a 2:1 wastewater ratio means that 1 gallon of water is wasted for every 2 gallons of water purified. The higher the wastewater ratio, the less wastewater is produced during the filtration process. When using an RO water purifier, the actual wastewater ratio may be lower than the nominal value, depending on a variety of factors such as water quality, pH, pressure, and temperature.