You cannot beat reverse osmosis water units when it comes to cleaning up water contaminated with salt. In that case they are worth the headaches. However, 95% of us get our water for a city utility company or from a chlorinated well that does not have a salt water problem. For us there is great news! Newer systems, called selective filtration, are simpler to install and use, cost less and produce healthier water than reverse osmosis. We will check out both systems in this article and you can decide.

Reverse osmosis (RO) systems work by pushing water against a semi-permeable membrane with pores so small that only objects the size of a water molecule, or smaller, will pass through. As a matter of fact, the pores are so small they will even reject a large part of the water itself along with minerals and most contaminants. In most RO systems, the rejected water is simply wasted. Typically, this amounts to about two or three wasted gallons for every gallon filtered.

The fact that minerals are screened out is why they were so popular with people who were also dealing with the things like iron and sulfur in their water. It is also the reason I implied above that the SF systems will produce healthier water.

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.

If you do decide on a RO system, be certain it comes with a carbon filter. This is because chlorine, a deadly poison, along with herbicides, pesticides, THMs, SOCs, drugs, etc., are made up of molecules smaller than water’s so they will not be removed by reverse osmosis systems.

Since the pores in the membrane are so tiny, you must have sufficient water pressure to force the water through the system and this may necessitate a booster pump be added.

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.

For most of us, using an RO system where you could use selective filtration is like using a backhoe to get a little crabgrass out of your yard. Sure, it’ll get the job done, but the ensuing pain won’t be worth it.

As an alternative to reverse osmosis systemes, let’s take a look at selective filtration. This is also known as multi-stage filtration.

Carbon is also used in these systems to take out any chemicals and drugs present in the water, however, this carbon has been blended with a filter resin that is chemically charged and the whole thing is extruded into a solid carbon block containing very fine, micron sized pores.

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.

There you have it, the water is cleaned but it still has its nutritious trace minerals. Selective filtration systems are quick, so there is no need for holding tanks with diaphragms. Nor is there any need for booster pumps, electricity, backwashing, etc., and, if installed correctly, they operate virtually maintenance free.

Be sure you consult a technical representative for any system you are considering if the water you want to treat has extreme problems. They folks will invariably have a good solution. Also, please note that selective filtration is not designed to treat salt water.

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