Archive for December, 2008
Basics of Drinking Water Filters
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.
First let’s look at the reverse osmosis (RO) systems.
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) Chemicals such as pesticides, drugs, chlorine, synthetic organic chemicals, etc. are not removed in the stage of the process since their molecules are smaller than water’s. A carbon filter must be used in combination with RO systems to finish the job.
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.
These systems will produce filtered water at a cost of 18 to 24 cents a gallon and maintenance is always among users’ chief complaints, along with costs.
Next up is the distillation system (D).
When the sun heats the earth the warm, moist air rises, cools in the upper atmosphere and falls back to earth again as rain or snow. That is a good example of distillation process.
Distillation systems send water over a heated coil, causing the water to turn to steam. The steam transfers to a cooling chamber where it condenses back to a liquid, leaving inorganic compounds like lead, calcium, mercury, etc. behind.
This system is very effective against bacteria. Any bugs chlorine might have missed, such as cysts like Cryptosporidium and Giardia (bad bugs), will be zapped by distillation.
The D systems have the same drawback as the RO systems, however, in that they remove the bad metals like lead but take out the beneficial trace minerals as well.
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.
Distillation like reverse osmosis is slow and incredibly wasteful, wasting up to 80 percent of the water used. Distillation produces water at a cost of 20 to 26 cents per gallon.
Selective filtration or multi-media block filtration is the last system we will look at.
Activated charcoal or carbon has long been viewed as the best technology for removing chemicals compounds such as chlorine, chlorine byproducts, herbicides, pesticides, drugs, etc., so, the earlier versions of these systems simply ran water through a cylinder filled with a granular form of activated charcoal.
However, these first systems:
1) Allowed some water to flow between the filter’s walls and the charcoal, so, not all the water was filtered and,
2) There was some concern that these filters were not capable of removing the tiny microbes such as Cryptosporidium and Giardia.
A new technology was developed which made the two complaints mute. This new technology kept the filtering power of activated charcoal but changed its form. First, they mixed the activated charcoal with a resin that had been chemically charged and compressed the mix into a solid block composed of 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.
And chemical pollutants are obviously filtered out by the activated charcoal.
That leaves the special resin you mentioned…what does it do?
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.
Just remember, whatever water filter you use, don’t let it be your body.
Tags: chlorine, filteration, heavy metals, pure water, toxins, water filters, water safety
