What does reverse osmosis do?  What is reverse osmosis, anyway?  Here, you'll find the answers to those questions and more. 

You see in nature, compounds travel from a direction of higher content to lower content.  So, if you throw a handful of dirt into a gallon of water, it will not simply stay there.  It will gradually contaminate the entire gallon.

That's the opposite of what does reverse osmosis do.  Pressurized liquids are forced through a membrane so that minerals and other substances heavier than the liquids are removed.

That's the simplest explanation that I have found.  The process is actually very complicated and difficult to explain.  To fully explain what is reverse osmosis, you need to understand more about the size and weight of water molecules as opposed to other substances.

So, what does reverse osmosis do to water?  It can be used to remove large particles of dirt from river-water and other sources.  It can remove rocks, stones, sand, etc.  It can also be used to remove salt, so you will find this step in a desalinization plant. 

What is reverse osmosis good for?  It is good for people that have brackish or only seawater to choose from.  It is also good in industrial settings that require demineralization to protect their equipment.  It is not good in most settings however, because of the disadvantages.

Most groundwater contains chemical contaminants.  Some of them cannot be smelled or tasted.  Many cannot be removed by treatment facilities.

Then there are tiny bacteria and other water-dwelling organisms.  Ingesting them can cause a group of illnesses known as waterborne diseases. 

In order to remove living or organic contaminants, a disinfection method is required.  In order to remove chemical or inorganic contaminants, carbon and multi-media blocks are needed.

So, the flip side of ?what does reverse osmosis do? is ?what does it not do?.  It neither disinfects nor removes chemicals.  It may be one step in a complete process, but it is never the only step if water is to be safe for human consumption.

Some companies sell the systems for home use and they are very expensive, but not because they are better than other types.  They are the only option for seawater, so there is some demand for their products.  It's just that for most people, they are unnecessary.
They are also wasteful and de-mineralized water is not good to drink.

The best answer to what is reverse osmosis good for has to do with kidney disease.  Dialysis machines use a form of the system to remove waste from the blood stream, taking the place of the lost kidney function until a transplant becomes available to the patient.

Hopefully this answers your questions about what does reverse osmosis do.  For water purification purposes there is a better choice.   

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