In this article, we will look at reverse osmosis, distillation and multi-media block filter systems. You will discover drinking water filters vary widely in effectiveness, required maintenance, speed of filtering, and cost per gallon of water produced. You will also acquire the information you need to choose the best drinking water filter system for your family.
Any of these filters are far better than continuing to use your body as a filter, but, depending on your water problems, you will find that some of them are clearly better than others.
Let's start with reverse osmosis (RO) systems since they are the biggest sellers.
The main filter in these systems is a semi-permeable membrane about the thickness of a piece of cellophane. Water that has been pre-filtered to remove most of the large particles is forced, under pressure, against the membrane and only particles the size of a water molecule, or smaller, can go thru. For the water conditions most of us have in the US, there is a far better way of doing what this stage does because:
1) This stage won't remove chlorine, chlorine byproducts, herbicides or most toxic synthetic organic chemicals, since their molecules are too small. Another filter, a carbon one, must be added to remove any chemicals and drugs present.
2) RO systems have to be operated under a minimum required pressure to force the water molecules through the filter, and even then, only about one-third of them get through and the rest of the water is wasted.
3) This process is very slow, producing a gallon or so of filtered water per hour, so, if you want any volume of water for a shower, you will have to add on a special storage tank.
4) This stage will get the lead out, but it also removes the minerals our bodies need such as potassium, calcium and magnesium. At that point, the water water has gone from being neutral to being slightly acidic, and some medical professionals believe such water is unsafe to consume on a long-term basis.
The RO systems require considerable maintenance and they produce comparatively expensive water at about 18 to 24 cents per gallon.
Now, distillation systems (D) are next.
Distillation is similar to nature's recycling system. In nature the sun heats the water; it evaporates and rises to the upper atmosphere, condenses in the cooler air and falls as rain.
In the D system, water is passed over a heated coil; the water vaporizes, goes into a cooling chamber and condenses back to a liquid. During this process inorganic compounds like lead, calcium, potassium and other minerals are removed.
Distillation also destroys and bacteria present. Chlorine-resistant 'bugs' like Cryptosporidium and Giardia, are also removed at this point.
We noted the D systems removes harmful metals like lead, but they also remove the healthful minerals like calcium and potassium just like the RO systems.
Another thing they don't remove, just like the RO systems, is chlorine and synthetic organic chemicals, because they vaporize more quickly than water and move right along with the water vapor. Consequently, D systems have to be used in combination with carbon filters.
D systems share a few other things in common with RO systems in that they are also slow and very, very wasteful, losing as much as 80% of the water they use. The D system will produce filtered water for 20 cents to 26 cents per gallon.
The last systems we will look at are called multi-stage or selective filtration systems.
In the earlier versions of these filters, the water was filtered by simply forcing it through a cylinder containing granular activated charcoal (GAC). The activated charcoal was used since it was recognized by the U.S. EPA as the best filtering medium for removing chlorine, volatile organic chemicals (VOCs) and synthetic organic chemicals (SOCs).
However, these basic designs:
1) Gave water a chance to pass along the walls of the filter and the charcoal so some of the water did not get filtered and,
2) There was a lack of confidence over these filters' ability to stop the extremely small, chlorine-resistant cysts such as Cryptosporidium and Giardia.
Both of these issues were resolved with the introduction of selective filtration utilizing multi-media block filters. This technology utilizes the advantages of the activated carbon by first blending it with a chemically charged filter resin and then extruding, or compressing, it into a solid block containing tiny, submicron pores.
The problems were eliminated since the water could no longer bypass the filter and the cysts were removed by the filter's tiny pores.
Also, we know the activated charcoal easily removes the chemical contaminants from the water.
What about the filter resin that covers the adsorption area of the charcoal?
That resin causes any heavy metal ions in the water from metals like lead or mercury to break their bonds with water and snap to this chemically charged surface like a magnet to a piece of metal. However, the lighter minerals, such as calcium and potassium do not join in on the ion exchange, so, bottom line, the good stuff stays in the drinking water.
When you think of the "Rube Goldberg-ness" of the RO or D systems it is easy to understand why selective filtration technology is leading the industry. Independent laboratory tests have proven the produce the highest quality water and initial costs are more than competitive.
And, the are efficient and economical, giving you clean water at about 9 cents a gallon, they work quickly, very simply (no extra pumps or electricity needed and no need for storage tanks) and, virtually maintenance free.
But, whatever you decide, please, don't use your body as the filter when you drink or bathe in chlorinated water.
Any of these filters are far better than continuing to use your body as a filter, but, depending on your water problems, you will find that some of them are clearly better than others.
Let's start with reverse osmosis (RO) systems since they are the biggest sellers.
The main filter in these systems is a semi-permeable membrane about the thickness of a piece of cellophane. Water that has been pre-filtered to remove most of the large particles is forced, under pressure, against the membrane and only particles the size of a water molecule, or smaller, can go thru. For the water conditions most of us have in the US, there is a far better way of doing what this stage does because:
1) This stage won't remove chlorine, chlorine byproducts, herbicides or most toxic synthetic organic chemicals, since their molecules are too small. Another filter, a carbon one, must be added to remove any chemicals and drugs present.
2) RO systems have to be operated under a minimum required pressure to force the water molecules through the filter, and even then, only about one-third of them get through and the rest of the water is wasted.
3) This process is very slow, producing a gallon or so of filtered water per hour, so, if you want any volume of water for a shower, you will have to add on a special storage tank.
4) This stage will get the lead out, but it also removes the minerals our bodies need such as potassium, calcium and magnesium. At that point, the water water has gone from being neutral to being slightly acidic, and some medical professionals believe such water is unsafe to consume on a long-term basis.
The RO systems require considerable maintenance and they produce comparatively expensive water at about 18 to 24 cents per gallon.
Now, distillation systems (D) are next.
Distillation is similar to nature's recycling system. In nature the sun heats the water; it evaporates and rises to the upper atmosphere, condenses in the cooler air and falls as rain.
In the D system, water is passed over a heated coil; the water vaporizes, goes into a cooling chamber and condenses back to a liquid. During this process inorganic compounds like lead, calcium, potassium and other minerals are removed.
Distillation also destroys and bacteria present. Chlorine-resistant 'bugs' like Cryptosporidium and Giardia, are also removed at this point.
We noted the D systems removes harmful metals like lead, but they also remove the healthful minerals like calcium and potassium just like the RO systems.
Another thing they don't remove, just like the RO systems, is chlorine and synthetic organic chemicals, because they vaporize more quickly than water and move right along with the water vapor. Consequently, D systems have to be used in combination with carbon filters.
D systems share a few other things in common with RO systems in that they are also slow and very, very wasteful, losing as much as 80% of the water they use. The D system will produce filtered water for 20 cents to 26 cents per gallon.
The last systems we will look at are called multi-stage or selective filtration systems.
In the earlier versions of these filters, the water was filtered by simply forcing it through a cylinder containing granular activated charcoal (GAC). The activated charcoal was used since it was recognized by the U.S. EPA as the best filtering medium for removing chlorine, volatile organic chemicals (VOCs) and synthetic organic chemicals (SOCs).
However, these basic designs:
1) Gave water a chance to pass along the walls of the filter and the charcoal so some of the water did not get filtered and,
2) There was a lack of confidence over these filters' ability to stop the extremely small, chlorine-resistant cysts such as Cryptosporidium and Giardia.
Both of these issues were resolved with the introduction of selective filtration utilizing multi-media block filters. This technology utilizes the advantages of the activated carbon by first blending it with a chemically charged filter resin and then extruding, or compressing, it into a solid block containing tiny, submicron pores.
The problems were eliminated since the water could no longer bypass the filter and the cysts were removed by the filter's tiny pores.
Also, we know the activated charcoal easily removes the chemical contaminants from the water.
What about the filter resin that covers the adsorption area of the charcoal?
That resin causes any heavy metal ions in the water from metals like lead or mercury to break their bonds with water and snap to this chemically charged surface like a magnet to a piece of metal. However, the lighter minerals, such as calcium and potassium do not join in on the ion exchange, so, bottom line, the good stuff stays in the drinking water.
When you think of the "Rube Goldberg-ness" of the RO or D systems it is easy to understand why selective filtration technology is leading the industry. Independent laboratory tests have proven the produce the highest quality water and initial costs are more than competitive.
And, the are efficient and economical, giving you clean water at about 9 cents a gallon, they work quickly, very simply (no extra pumps or electricity needed and no need for storage tanks) and, virtually maintenance free.
But, whatever you decide, please, don't use your body as the filter when you drink or bathe in chlorinated water.
About the Author:
David Eastham has done a great deal of research on such topics as reverse osmosis to discover the best way to provide good, clean drinking water. Go here now for his selections as the best dollar for dollar purchases, and the best products overall, in water filtration technology.
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