Reverse Osmosis Units-Great If You Need One-But Do You Need One?
Posted Nov 18 2008 12:37am
by David Eastham
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.
The fact is we need some minerals left in the water because our bodies need them. The second largest component in our body after water itself is calcium. If we constantly drink water with no minerals we are drinking water that is slightly acidic and it wants to return to its neutral state. One way for it to do that is to swipe some calcium from our cells, bones or teeth to produce calcium carbonate, a neutralizing compound.
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.
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.
All in all, they are bulky units, what with the filter, a storage tank, and, maybe, an extra pump. All of this often means more expense, usually requires a plumber to install, and leads to extra maintenance cost somewhere down the line.
Anymore, I feel like using a RO system where you could have used selective filtration is like hunting flies with a cannon…they’re clunky, expensive and give a dangerous result.
As an alternative to reverse osmosis systemes, let’s take a look at selective filtration. This is also known as multi-stage filtration.
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.
One cubic foot of this activated charcoal that has been so tightly compressed has the adsorption area of five square miles, according to scientists. The tiny pores filter out tiny, chlorine-resistant, cysts like Cryptosporidium and Guardia and the rest of the surface area scrubs up the chemicals and drugs.
Why does the adsorption area have the chemically charged resin?
When heavy metal compounds such as mercury or lead come in contact with this resin, their positively charged ions break their bond with water and snap onto the resin like little magnets. Because of the difference in their molecular structure, the lighter metals such as potassium and calcium don’t react and remain in the water.
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.
About the Author:
David Eastham has done exhaustive research on such topics as reverse osmosis to find the best way to provide good, clean drinking water. Follow him for his picks as the best dollar for dollar buys, and the best products overall, in water filtration systems.