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.
A semi-permeable membrane is the work horse of these units. Water is forced against the membrane and all particles larger than a molecule of water are rejected. These pores are so very tiny it often becomes impossible for water molecules themselves to pass through and, consequently, a gallon or more of water can be thrown out, along with any filtered contaminants and minerals, for every gallon that gets through the filter.
Hard water or water with excessive minerals is a problem in many water supplies and the fact that RO systems remove these minerals is another plus for these systems. However, it also has been found to cause another problem.
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.
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.
Reverse osmosis will not remove contaminants such as drugs, chlorine, THMs (chlorine byproducts-carcenogens), herbicides, pesticides, SOCs, etc. because molecules are very small and will pass through the membrane. The EPA recognizes activated charcoal as the best filter for removing these compounds and you must be certain you have one if you go the RO route.
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.
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.
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.
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.
And the chemically charged filter resin...what does that do?
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.
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.
Article Source: http://www.alltopinfo.com
David Eastham has done exhaustive research on such topics as selective filtration to discover 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 water filtration technology.
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