It’s true, if you have salty or brackish water with a lot of inorganic material in it, you will be pleased with anything that will clean it up and reverse osmosis water units will. But, if you are getting your water from a municipal water system or a chlorinated well; I’ve got good news for you. There are much cheaper selective filtration systems you can get that will do a better job, and produce healthier water, than reverse osmosis systemes. In this article we will look at each system and how they work, and you can decide what’s best for you.

The RO system works by forcing water against what is called a semi-permeable membrane. The membrane’s pores are so tiny that any object larger than a molecule of water will not pass through it. Often, water molecules cannot get through either and, usually, this water is simply discarded along with any minerals or contaminants that have been screened. In general, these systems reject two or three gallons of water for every filtered gallon produced.

Some people throughout the US are also dealing with excessive minerals in their water and the fact that RO systems remove these minerals is another reason people have liked them. But, too much of a good thing can be bad.

You see, it seems water with no minerals is not good. That makes sense since nowhere on earth does pure water exist naturally. We need trace minerals like calcium and potassium, for example, in order to stay healthy. And, pure H2O is slightly acidic, so, when we drink this water it will try to get back to a neutral state by stealing minerals such as calcium from our teeth, bones or cells. In this case it produces calcium carbonate as its neutralizing element.

Since cancer cells seem to prefer environments which are slightly acidic, some health professionals are now questioning the wisdom of drinking such water over a long period of time.

When it comes to synthetic organic chemicals (SOCs), they usually have a smaller molecular structure than water, and will pass right through the membrane. These are compounds like herbicides, pesticides, etc. In order to get the dirty SOCs out of the water, RO systems must be used in combination with a carbon filter.

RO systems requires adequate water pressure to force the water against the membrane and, for some users, this may call for the addition of an inline booster pump.

If you want to have more than just drinking water from an RO system you will need to add a storage tank, since these systems only filter a gallon or so of water per hour. In order to keep a constant pressure on the system a tank with a diaphragm is normally used.

By the time you put all the storage tanks, extra pumps (if needed), and filters together you are going to have a good sized unit. Anytime you have a lot of components you are likely going to be dealing with extra initial and operating costs, and maintenance issues.

Like I said, where they are good (with brackish water), RO systems are very good. But, as they have progressed to solve chemical problems, flow rate problems, etc.; they have become very Rube Goldberg like.

Selective filtration is also called multi-stage filtration and it is a good alternative to reverse osmosis.

In selective filtration systems, carbon is mixed with a filter resin that has been chemically charged, and this mixture is then compressed into a solid block that has very small, submicron pores. The carbon, or course, removes chemicals and drugs that might be present in the water.

It’s interesting that scientists say a solid block of activated carbon, one foot square on each side, has an adsorption area of five square miles! No wonder is does so well with chemicals and it still has plenty of capacity in the tiny pores to clean up chlorine-resistant cysts, like Cryptosporidium and Guardia and any remaining debris.

What about the filter resin that covers the surface of the adsorption area?

Heavy metals, such as mercury or lead, have positively charged ions. When they pass over the chemically charged resin they are drawn to the resin as if they were magnets. Other metals, like calcium or potassium, pass by unaffected.

You noticed these systems don’t have bulky storage tanks, they don’t need booster pumps or electricity and, if they are correctly installed, they produce good, healthy water (all trace minerals intact) virtually without maintenance.

Should you happen to be dealing with a severe water problem, is always wise to consult with a technical representative for any system you are planning to use. They know their business and can almost always suggest a solution. If you have salty water, you should be aware that selective filtration is not designed to remove salt.

Popularity: 1% [?]