Reverse Osmosis Water Filter:

What's in Your Water Filter? It's Called Reverse Osmosis!

Reverse Osmosis Water Filtration and You

by Josh Day

Reverse osmosis, now that's a mouth full.

I'm sure you've heard of it before. But do you really understand what it is and how it works?

Let's go to Wikipedia:

Reverse osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. This is the reverse of the normal osmosis process, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied. The membrane here is semipermeable, meaning it allows the passage of solvent but not of solute.

The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–70 bar (600–1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure which must be overcome.

This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but it has also been used to purify fresh water for medical, industrial and domestic applications since the early 1970s. (Wikipedia)

If you want it in more layman terms, I defined it myself in another article:

The creme de la creme of filtration is water purified by reverse osmosis. This process is so powerful that it's been called hyperfiltration. Water is passed through a membrane so fine that it can remove pretty much anything. There are also several stages of pre-filtration, as well as a storage tank for purified water. Obviously, this system [...] would take up some amount of space... imagine having a miniature treatment plant under your sink!

If you've read my other articles on water, you'll know I keep a number of fish tanks of varying size and salinity (at one point I kept fresh, brackish, and saltwater systems). Reverse osmosis is the ideal form of water in marine aquariums as its pure and comes out at 6.0 pH, which is great for mixing synthetic salt. Nitrates, phosphates, copper, chlorine, and everything else that hitch along to your faucet tap are things you don't want anywhere near sensitive marine life. Reverse osmosis removes these impurities.

Reverse osmosis is the Superman of carbon. It can even pull out fluoride, which is a reduced form of the element fluorine. Unfortunately, you may not want to drink reverse osmosis on a regular basis as the water is actually too pure -- minerals are lost along with toxins in the process (2010 update: Click here for information contrary to that statement, which may very well be wrong). Even the most natural, pure water on the planet, glacial water, appears microscopically "dirty" next to reverse osmosis water.

Another drawback of reverse osmosis water filters are their output. For every gallon of purified water, you can lose up to several gallons in the process, depending on the quality of your filtration system. The reverse osmosis system is quite bulky and consists of several cylinders and a network of tubing.

Yet one more con for reverse osmosis is the cost. With systems starting at about $260, the price only goes up.

If you want pure, clean water, consider a non-reverse osmosis water filter like the one described below. The fluoride stays in, but a lot of other things -- including pesticides and herbicides -- are removed.

Editor's Note: Click here to visit the site where we purchased our water purifying unit that produces crystal clear healthy water for less than 10 cents a gallon. We like our Multi-Pure filter that we bought from this company so much we became a distributor.

Disclaimer: Throughout this entire website, statements are made pertaining to the properties and/or functions of food and/or nutritional products. These statements have not been evaluated by the Food and Drug Administration and these materials and products are not intended to diagnose, treat, cure or prevent any disease.