Q. What is reverse osmosis (RO)?
A. Reverse osmosis is a purification process where water is demineralized using a semipermeable membrane that separates and removes a high percentage of unwanted molecules. The process reverses the principle of osmosis which occurs in nature and is most commonly identified in plants. Each plant cell is also a semipermeable membrane allowing only water molecules through and leaving dissolved solids and salts behind. Another fundamental principle is also important to understand reverse osmosis. That is, dissimilar liquids when separated by a semipermeable membrane will attempt to reach the same Pressure concentration or equilibrium. This is known as natural osmotic flow as indicated in the diagram below. The goal of our purification system is to remove dissolved salts and solids from water. It is necessary to reverse this natural osmotic flow by forcing the water with the higher concentration of salts and solids (your tap water) through the membrane in the reverse direction.

Q. What happens to the dissolved solids, salts and other contaminants?

A. The reverse osmosis membrane employs cross flow filtration as shown in the figure on the right. In cross flow filtration, the tap water is split into two parts - the purified water which is directed to the holding tank and the concentrated contaminant stream of water is rejected by the membrane and sent to drain.