What Is Reverse Osmosis Filtration?

What Is Reverse Osmosis Filtration?

Reverse osmosis filtration is one of the best methods for comprehensive water purification. It works by “reversing” something called “osmosis.” Osmosis is the natural movement of water molecules in a solution with a high number of them to a solution with a lower number of them. This movement continues until an equal distribution of water molecules is achieved.

Reverse osmosis filtration, also known as RO filtration, applies enough pressure to overcome this natural “osmotic pressure” to force unpurified water through a semi-permeable membrane perforated with 0.0001-micron pores. Microscopically small, virtually the only things that can slip through these pores are water molecules.

RO filtration famously removes from water something called total dissolved solids (TDS). Examples of TDS include salts, PFAS, nitrates, fluoride, and heavy metals like lead and arsenic. Neither ultrafiltration (0.1 to 0.01 micron pores) nor nanofiltration (0.001 micron pores) can achieve that level of contaminant reduction.

Originally developed to desalinate sea water, RO filtration has become a popular water purification system for homes and offices. Available in both undersink filtration systems and water dispensers, the RO filtration process works the same in each one.

The RO membrane is usually the third stage in a multi-stage system. Typically, it’s preceded by a sediment stage and a granular activated carbon (GAC) stage. It’s then followed by a post carbon or carbon block stage, and often an alkaline stage that reintroduces beneficial minerals to the purified water that were removed during the RO filtration.

Incoming (or feed) water first passes through the sediment and GAC filters, where it undergoes prefiltration. These stages remove solid particulates and chlorine. (The removal of chlorine is crucial as it will damage the RO membrane.) The water then enters the reverse osmosis cartridge where the membrane is housed.

As this is the key filter in a reverse osmosis filtration system or dispenser, it’s worth briefly describing its structure.

The membrane element is composed of multiple spiral-wound layers. Each layer consists of two RO membranes that sandwich a porous sheet called a permeate carrier. This “sandwich” is glued together on three sides to form an envelope. The open end of this envelope is attached to the center permeate tube which is perforated with tiny holes into which the permeate (purified water) is channeled.

After all the envelopes are attached, a mesh feedwater spacer is placed between each one. The assembled layers are then wound around the permeate tube to form the membrane element, which is inserted into its cartridge or housing. The addition of the mesh spacers will ensure the feedwater is evenly distributed throughout the membrane element.

As previously mentioned, water pressure forces the now prefiltered feedwater into the RO element, where TDS contaminants are blocked from proceeding. The now-purified water moves into the permeate tube. From there it either travels on to a final filtration stage or stages, or to a storage tank or dedicated faucet for immediate dispensing.

Up to 99.97% of contaminants are blocked during reverse osmosis filtration. These rejected contaminants form a brine that’s automatically and regularly flushed out of the system and into a wastewater tube that’s connected to an external drainpipe.

What Are the Benefits of a Reverse Osmosis Filtration System or Dispenser?

The number one benefit? Peace of mind.

With 0.0001-micron pores, a reverse osmosis membrane can remove a broad swath of dangerous contaminants. So when you install a reverse osmosis filtration system or dispenser, you ensure fresh, clean water is easily accessible. This, in turn, empowers everyone in the household to make healthier hydration choices. And don’t forget pets. They prefer (and need) fresh, clean water too.

As well as being great for drinking, RO-purified water is also ideal for preparing baby formula, tea, coffee, and cocoa, as well as cooking hot cereals, soups, rice, and pasta.

And because an RO filtration system works with your home or office’s own water system and typically comes with a dedicated faucet, purified water is always available. No need to sign up for an expensive bottle delivery service and no worries about water bottles running low.

Another huge plus of putting in a reverse osmosis filtration system or dispenser? Kicking the single-use plastics habit to the curb for good. Not only do repeated purchases of water bottles add up over time, the negative impact of these bottles on health and the environment is catastrophic. An in-home or in-office RO system makes it incredibly easy to switch to reusable sports bottles and glasses.

With a decaying water infrastructure that received a grade of C-minus on the 2021 report card issued by the American Society of Civil Engineers, contaminants of emerging concern, and sudden disasters like train derailments, it pays to be prepared. 

At Brio you’ll discover a wide selection of high-quality reverse osmosis systems and dispensers that provide solutions to your drinking water concerns. We use only premium materials and components, and our reverse osmosis membranes are certified NSF/ANSI 58, which is the industry gold standard for the removal of TDS.

Reverse osmosis filtration is an ideal way to secure your water, so you always know it’s safe.




Back to blog

Leave a comment

Please note, comments must be approved before they are published