Whole house water purification means just what it says. The idea is to filter all the water coming into your home by installing a water filter system near the point your water supply line enters the home. That way all the water past that point has been filtered and you can have good, safe water everywhere, in your sinks, showers, bathtubs and even for laundry and the dishwasher. In this article we will look at whole house water purification systems, what they do, how they do it, and the best technology to use to get the job done.
1. What should a good home water purifier do?
It should take polluted water and give you back good, clean, healthy water. A good whole house water purifier will remove over ninety-nine percent of the harmful contaminants from the water. Contaminants like chlorine, the deadly chlorine byproducts (THMs), synthetic organic chemicals (SOCs), herbicides, lead, legal and illegal drugs, excess minerals, etc.
2. How are these systems able to get out all of these pollutants?
You need to know home water purifiers are not just one big filter. They are made up of a number of filters, each of which has an assigned task. The first filter the water encounters is called a pre-filter and its job is to clean out any large globs like dirt, debris from pipes, etc. that could harm later filters.
The best filter for removing the deadly chemical compounds that are showing up more and more in our water supplies is activated charcoal. So, a filter with activated charcoal will follow next, since there no technology has been found that will do a better job.
The third stage of filtering could come from distillation, reverse osmosis, or a system utilizing the adsorption power of activated charcoal, sub-micron filters and ion exchange called selective filtration or multi-stage filtration.
The distillation process works by heating water until steam forms and that steam is moved to a separate chamber to cool and return to a liquid state. During the process bacteria is killed and inorganic compounds such as lead, potassium, calcium, etc are removed. The process cannot handle organic chemicals very well so distillation must be used together with carbon filtration.
The electricity used in the process of distillation creates a high energy cost and these units are very slow, producing less than four gallons a day of filtered water.
Reverse osmosis units push water against a semi-permeable membrane with very fine pores, the size of water molecules. The process rejects certain contaminants, minerals, and even a large part of the water itself. Most SOCs, such as herbicides and pesticides, are smaller, molecularly, than water and will pass through the membrane and will not be filtered out. That is why these systems must be used in combination with a carbon filter.
Most reverse osmosis systems produce only a gallon or two of filtered water an hour and will waste two or three times that for every gallon produced. They require a storage tank to create any volume of filtered water and, sometimes, a booster pump as well to maintain pressure. Initial costs for the various components and maintenance costs make these units about equal in cost with distillation.
Since both of these systems remove all minerals from the water, including healthy trace minerals the body needs, a problem is created. Water in this condition becomes a little acidic and, after we drink it, it will have a natural tendency to return to a neutral pH. It does that by pulling calcium from our body. For this reason, some medical professionals feel this water is unhealthy to drink.
The third system starts with the adsorptive power of activated charcoal and it is blended with a chemically charged resin to create a very different, but highly effective, filter media.
This mixture is compressed, or extruded, into a solid block of carbon whose core structure contains small, sub micron pores. As water passes through the carbon block, chemicals, drugs, etc. are physically bonded to the activated carbon. Any cysts such as cryptosporidium and giardia are trapped by the tiny pores, as are any remaining inorganic compounds. Finally, the chemical resin forces the ions of heavy metals, such as lead, to break their bonds with water and the resulting compounds can be trapped by the surface of the filter.
Brackish or salty water cannot be handled by selective filtration systems. However, this would only be an issue with about 5 percent of households in the U.S.
Selective filtration does not require any electricity and, since the system operates quickly, they don't need storage tanks either. Also, they barely impede the water flow so no booster pumps are needed. Another big factor is they cost less to purchase and operate than either of the other two systems.
3. Of the three systems, which one should you choose?
Reverse osmosis is the only way to go if you a fighting a salt water problem. They are not the cheapest systems to own and operate, but they are by far the best solution for brackish water.
Barring a salt water problem, I don't think you can beat selective filtration for the quality of water produced, or for the price. The unit cost is the lowest and they should operate almost maintenance free, only needing a periodic filter change.