That's right, reverse osmosis water units are hard to beat when you have a problem like salt in your drinking water supply. But most of us don't have that problem; we get our water from a municipal supplier or from a chlorinated well. And, for those people, I've got good news indeed. You will get a better result from selective filtration systems than you ever could with reverse osmosis. In today's article we will examine both systems and how they differ. Then you can decide which one is best for your situation.
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.
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.
Medical professionals also tell us cancer cells appear to always grow in environments which are slightly acidic, so, they think there can be an increased cancer risk for people drinking mineral-free water.
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.
If the water pressure in your home is too low, reverse osmosis systemes will require the addition of an inline booster pump in order to operate properly.
Another requirement of these systems is a storage tank, with a diaphragm to maintain pressure, because most RO systems produce less that one gallon of filtered water per hour. At that rate, without a storage tank, you simply wouldn't have enough clean water for bathing or doing laundry or much of anything else.
As you can see, these systems with their filters, storage tanks, and, perhaps, an additional pump are sizeable and, as you might imagine, they are relatively expensive, somewhat difficult to install and subject to extra operating and maintenance costs.
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.
Now, let's look at an alternative to reverses osmosis, the selective (or multi-stage) filtration system.
These systems also use activated carbon to clean up any drugs or chemicals that might be in the water, but this carbon is first blended with a chemically charged resin and compressed into a solid block composed of tiny, submicron pores.
This carbon has a huge filtering capacity. They say a cubic foot of compressed activated carbon like this has a filtering area of five square miles! Plenty of capacity to clean up chemicals, and it also takes care of things like Cryptosporidium and Guardia (chlorine-resistant Cysts), and any remaining inorganic contaminants, with the submicron pores.
Why does the adsorption area have the chemically charged resin?
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.
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.
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.
Medical professionals also tell us cancer cells appear to always grow in environments which are slightly acidic, so, they think there can be an increased cancer risk for people drinking mineral-free water.
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.
If the water pressure in your home is too low, reverse osmosis systemes will require the addition of an inline booster pump in order to operate properly.
Another requirement of these systems is a storage tank, with a diaphragm to maintain pressure, because most RO systems produce less that one gallon of filtered water per hour. At that rate, without a storage tank, you simply wouldn't have enough clean water for bathing or doing laundry or much of anything else.
As you can see, these systems with their filters, storage tanks, and, perhaps, an additional pump are sizeable and, as you might imagine, they are relatively expensive, somewhat difficult to install and subject to extra operating and maintenance costs.
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.
Now, let's look at an alternative to reverses osmosis, the selective (or multi-stage) filtration system.
These systems also use activated carbon to clean up any drugs or chemicals that might be in the water, but this carbon is first blended with a chemically charged resin and compressed into a solid block composed of tiny, submicron pores.
This carbon has a huge filtering capacity. They say a cubic foot of compressed activated carbon like this has a filtering area of five square miles! Plenty of capacity to clean up chemicals, and it also takes care of things like Cryptosporidium and Guardia (chlorine-resistant Cysts), and any remaining inorganic contaminants, with the submicron pores.
Why does the adsorption area have the chemically charged resin?
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.
About the Author:
David Eastham has done extensive research on such topics as reverse osmosis to find the most economical way to get good, clean drinking water. Here are his picks as the best dollar for dollar buys, and the best products overall, in home water filtration technology.
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