Reverse Osmosis Units-Great If You Need One-But Do You Need One?
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.
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.
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.
Selective filtration is also called multi-stage filtration and it is a good alternative to reverse osmosis.
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.
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.
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.
If you have a really gross water condition to remedy, it is always wise to talk to a technical representative for any filter system you are considering. These techs are great and they almost always have a solution. And, please note, selective filtration is not designed to treat brackish or salty water.
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