What is Reverse Osmosis?
Reverse Osmosis (RO from hereon in), is a process to de-mineralize or de-ionize water by pushing it under pressure through a semi-permeable, one-way RO Membrane. The membrane works to separate contaminants from the water you want to use. Think of it as a very fine mesh with holes large enough to let through molecules of water but too small to allow “unwanted” particles to pass through. RO can remove many types of dissolved and suspended particles from water. This includes particles of bacteria.
RO is used within industrial processes to purify water e.g. within some parts of the print industry. Military equipment revolving around RO has been deployed to areas of natural disaster to clean up contaminated local water quickly – giving the ability to make drinking water safe on the spot without importing quantities of clean water from outside the area.
Osmosis refers to the natural process by which unsalted (i.e. pure) water “flows” through permeable barriers towards salted water (impure). In essence, an attempt to de-salt the stronger solution. At the heart of the RO process, applying pressure at the barrier (the membrane) acts to reverse the direction of flow. As impure water flows through, the membrane “catches” the impurities and separates them from the clean water.
Although the phenomenon of osmosis was identified in the 1700s, no commercial applications were identified until the 1950s when RO was used to de-salinate seawater by a team at UCLA. Our use of the technology has grown ever more sophisticated since then.
What are the claims for RO?
RO works because “unhealthy” molecules are larger than the desirable and “healthy” molecules of water. An RO Membrane is a physical barrier – a mesh with minutely small pores (holes). Water will flow through holes which are 0.0005 microns in diameter. A molecule of sea salt is .0007 microns – too big to pass through. Pesticides are typically measured at 0.001 microns – too big. Living bacteria are between 0.4 and 1.0 micron – way too big for our mesh.
So on the surface there is a powerful natural process that we can exploit to improve the quality of water available to us. It has been proven to work. The Centres For Disease Control and Prevention (CDC) of US Department of Health confirms that an RO membrane will block health hazards such as Cryptospiridium, Salmonella, Hepatitis A and Norovirus as well as sodium, chloride, copper, lead, potassium and other common chemical contaminants.
What are the drawbacks of RO?
It isn’t all good news. The process works, but it is pretty slow. Although it is effective, it is not efficient. It’s estimated that a simple system would take about three minutes to fill a glass with clean liquid. There is a lot of waste in the process and the RO membranes are so delicate that they need to be protected by other filters that help them work. In other words, we can’t rely on an RO membrane by itself to purify our water. To get industrial levels of throughput, the water needs to be boosted to a high level of pressure. That military equipment is sophisticated and high-powered.
On top of that, not everything in your water is bad. Our bodies need intakes of calcium and magnesium for example. Normally this comes from our water supply. The membrane of an RO system is impermeable to natural trace minerals like these. What we have found is that these minerals not only provide a “good taste” to our water, they also serve vital functions to keep our body working. Water, when stripped of these trace minerals, can actually be unhealthy for us!
How is it used in home water purifiers?
You can install water filtration systems at home without using an RO element. That may be enough for your own use. It really depends on the quality of water in your local area. But the most sophisticated and complete solutions implement an RO membrane somewhere in the system.
When it comes to using this technology at home, you’ll find a range of options. Each of them uses an RO Membrane at the heart of a multi-part filtration system. Several layers of filter support and protect the precious membrane to give it as much chance as possible to work. Efficiency is countered by installing a “holding tank” of purified water which is kept clear of the membrane after it is filtered. As further layers of protection, you’ll even find filters installed after the tank.
You’ll see systems described as Point Of Use or Point Of Entry.
Point of Use refers to a small set of filters that you’ll install under a sink or basin. They’ll filter the water to that particular outlet or tap. Pricing will be less than $500 dollars. It’s almost a do it yourself job. The unit is equipped with disposable filters that will need to be refreshed on a regular basis. The unit pictured here will support up to 50 gallons of cleaned water per day. Larger units are available.
A Point Of Entry unit is introduced on your side of the water meter but acts to clean all water as it comes into your premises. A “whole house” system like this will cost you more like $2,000 but then every tap in your house will provide sparkling clean water. The reason this is installed on your side of the meter is down to the poor efficiency of the filtration process – you’ll pay for a lot of “wasted” water.
Does Reverse Osmosis Remove Bacteria? Conclusions
There is no doubt that a Reverse Osmosis based water filtration system will remove bacteria from your water. Bacteria and a whole lot more. The RO systems you can put in place today are highly effective at cleaning your water supply to ensure you get the most benefit. The RO process will remove a wide range of contaminants. The costs are manageable as well. But you should check the details of your own current supply to see if it is economically viable for you. You may already have nothing to worry about. But you may have plenty to gain from installing an RO Membrane based system. You can read our impartial reviews here on various different brands and choose the one that’s best for you and your home.