What is Reverse Osmosis and How Does It Work?

Reverse Osmosis or “RO” as it is typically known, is a specific type of water filtration. 

A Reverse Osmosis water filter works by forcing water through a semi permeable membrane. 

With a typical contaminant removal rate of 0.0005 microns, most bacteria, viruses, cysts, fluoride, salts, heavy metals and sediment are substantially removed, leaving you with clean and clear water for use. 

What Is Reverse Osmosis? 

Reverse Osmosis refers to the movement of water (H2O) under pressure through a semi permeable synthetic membrane. The membrane is a thin film or skin that allows water (H2O) to pass through it while holding back the majority of contaminants. These contaminants are then rinsed away to drain via a waste line. Reverse Osmosis is commonly used in Australia for desalination of sea water for drinking purposes with large plants in most capital cities.

How Does Reverse Osmosis Work?

Osmosis is a fundamental Scientific Principal. In essence, two different concentrations of liquids within the same system will try to reach equilibrium (i.e. the same concentration of contaminants) on both sides of a barrier or membrane. 

If you place a membrane between two compartments in a container and then place salt water in one half of the container and pure water in the other half, the pure water will pass through the membrane to the saltwater side in an attempt to dilute the salt solution.

This attempt to reach equilibrium is called osmosis.

Reverse Osmosis is the reversal of the natural flow of osmosis. In a water purification system, the goal is not to dilute the salt solution, but to separate the pure water from the salt and other contaminants. When the natural osmotic flow is reversed, water from the salt solution is forced through the membrane in the opposite direction by application of pressure - thus the term reverse osmosis

How Does It Work For Drinking Water? 

Through the Reverse Osmosis process, we are able to produce pure water by screening out the salts and other contaminants.

The material of the membrane is semi-permeable; it allows water molecules to pass through while acting as a barrier to dissolved solids (i.e., mineral & chemical contaminants). The pores of the membrane are too small for the contaminants in water to pass through them.

Drinking water Reverse Osmosis Filtration Systems have multiple filters and stages of filtration. 3 & 4 stage systems are most popular for drinking water purposes. These additional filter stages assist by removing some of the sediment and contaminants in the water prior to the membrane, increasing its lifespan. 

Reverse Osmosis systems produce or filter the water slowly (8-10 litres/hour), with the water then stored in a container or tank. Due to the design of the Aqua Safe System, the storage tank can be located away from the system, in another cupboard or under the house, saving room while providing more flexibility. 

Under Sink Reverse Osmosis Systems are automatic in operation, when a certain amount of water is used from the storage tank, the RO System starts operating to refill and replace the water used. No power is required, it simply uses town water pressure.

Why Do You Need a Reverse Osmosis System?

Reverse osmosis (RO) is the most economical method of removing up to 99% of all contaminants.

Quality Reverse Osmosis membranes reject practically all particles, bacteria and organics, giving them a great advantage over traditional filtration methods, which often focus on specific elements within the water. 

Out of all the filtration methods, it removes the most contaminants in an easy to operate filtration system.

What Is the Best Reverse Osmosis Water System?

The ASRO4 manufactured by Aquasafe is the most popular choice when it comes to Reverse Osmosis. These systems are manufactured from quality components and filters sourced from the USA and UK. They feature 4 stages, commencing with a sediment filter followed by a carbon filter, the membrane, and a further carbon filter. Specialised cartridges can also be optioned to pH balance, produce alkaline water, further purify the water, or protect the membrane against hard water, making these a 5-stage system. 

Benchtop Filter Systems such as the ASBTRO4 are portable and great for when you are renting or are unable to plumb into the mains water supply. These 4 Stage systems are perfect for filling your water container as required then turning off again and storing out of the way. They don’t have the requirement of a storage tank as you make the pure Reverse Osmosis water when needed for the day. 

How Much Does a Reverse Osmosis Water System Cost?

Various Reverse Osmosis systems on the market can start in price from $200, however check the quality of materials at this price point. There is also no need to spend thousands of dollars to guarantee excellent water. Ensure that the system is comprised of quality fittings, filters and most importantly a highly rated membrane with readily available replacements of all these. A good guide would be in the $500 - $1000 range for a system that will last and keep you in quality water for many years. 

Aqua Safe has a basic 3 stage system, known as the RO3 that will produce quality water for as little as $499. 

Reverse Osmosis replacement cartridges usually cost around $50 each. The annual service cost for a Reverse Osmosis system is approximately $100 p.a for a three or four stage system for the pre-filters, plus the cost of any ancillary filter or membrane (generally 3-5 yearly) that may need replacement at the time.

Contact Us Today!

Check out our latest range of Reverse Osmosis Water Filters and Cartridges. We also supply an extensive range of Whole House Filter Systems, Countertop Systems, Under Sink Filter Systems & Fluoride Filter Systems. Take a look at the Water Quality in Your Area.If you would like further information or to discuss your unique situation, get in touch by calling us on 1300 661 735 of via our Contact Us page

Frequently Asked Questions

Do all Reverse Osmosis systems remove fluoride?

A Reverse Osmosis membrane will remove or reduce fluoride from the water. The amount of fluoride removed depends on the type and quality of the membrane utilised in the system. Typically you would see over 95% reduction with a quality membrane and system.

What does Reverse Osmosis remove from water?

Reverse Osmosis removes an extensive list of contaminants, including bacteria, chemicals and heavy metals. Refer to the table located on this page for further details.

Can Reverse Osmosis remove bacteria?

Reverse Osmosis systems are very effective are removing different forms of bacteria from the water. To ensure ongoing removal to a high level, the system must be serviced and filters replaced on a regular basis.

Does Reverse Osmosis water dehydrate you?

Reverse Osmosis water contains substantially purified H20. Reverse Osmosis water is ideal for hydration as it doesn’t contain any impurities.

Do Reverse Osmosis Water Systems waste water?

Efficient Reverse Osmosis systems will create approximately 1 litre of pure water per 1litre of waste water (known as permeate). This is generally plumbed directly to drain or can be captured for use on your garden or for other uses. Much better for the environment than bottled water.