Brackish water that contains mineral and salt content of less than 10,000 ppm can be efficiently processed by using brackish water reverse osmosis systems. The effective removal of minerals and salts turns water that is unsuitable for drinking, irrigation, or industry into a source of pure water.

Brackish water reverse osmosis water treatment systems utilize brackish water reverse osmosis membranes designed to process water with higher salt concentrations and under higher operation pressures than membranes used to filter tap water. The high salt concentration of the feed water increases the osmotic pressure of the solution. In order to reverse the natural effect of osmosis, caused by osmotic pressure, the operation pressure of reverse osmosis water treatment systems must be higher than the osmotic pressure. In brackish water reverse osmosis systems, the operational pressure is between 200 psi and 450 psi. The higher working pressure requires components specially designed to operate under higher pressure, such as pumps, RO membrane pressure vessels, fittings, and piping. This is why brackish water processed through reverse osmosis water treatment systems is more expensive than tap water systems. However, the brackish water reverse osmosis water treatment systems have a similar design with tap water reverse osmosis water treatment systems.

Reverse osmosis water treatment systems that process brackish water require a good pre-treatment system, including either the injection of an anti-scalant or the use of a water softener. As with tap water systems and even sea water reverse osmosis systems, the feed water goes into the multistage centrifugal pump and then passes through the membrane elements of the reverse osmosis water treatment system. After the feed water passes through the reverse osmosis membranes, it is separated into two streams: the product water called permeate and the reject water called concentrate. The permeate is collected in a storage tank to await consumption and the concentrate is flushed down the drain. In some cases, the brackish water reverse osmosis systems can be equipped with a concentrate recycle valve. This valve helps increase the overall recovery rate of the reverse osmosis water treatment systems by returning at least part of the concentrate to be reprocessed.