KDF/GAC filter units use a unique three-stage multi-media system that incorporates the latest advances in water treatment technology. This system removes the widest spectrum of contaminants, rivaling the effectiveness of reverse osmosis and distillation systems costing two to four times more, while preserving the beneficial minerals like calcium and magnesium.
STAGE 1 - MECHANICAL FILTRATION
Mechanical filtration is achieved when the dimension of the particle is larger than the hole in the filter. This form of filtration removes suspended particles, such as silt, sediment, sand, rust, dirt, and other undissolved matter. Our cartridge system employs a staged mechanical system that is measured in microns. As a point of reference, 1 micron equals 1/25,000 of an inch and a human hair is about 100 microns in diameter. As water enters the cartridge, it passed through a 1 micron prefilter (5 micron on CT-E and IL). The double under counter filter (UCD) and whole house filter (WH) use a 1 micron replaceable prefilter for sediment and cyst (Giardia, Cryptosporidium) removal. The optional ceramic prefilter cartridge (UCD-C) filters down to 0.5 micron to remove not only sediment and cysts, but bacteria as well.
In the next stage, the water passes through a bed of a media made of a special high-purity alloy blend of two dissimilar metals - copper and zinc KDF-55D This media, patented in 1987 by KDF Fluid Treatment, Inc., is a major advancement in water treatment technology that works on the electro-chemical and spontaneous-oxidation-reduction (redox) principles. Chlorine is instantaneously and almost inexhaustibly oxidized. Tests on our cartridge have shown 99+% chlorine removal past 20,000 gallons of water while a carbon cartridge of comparable volume drops below 90% effectiveness after only 4,000 gallons. Iron and hydrogen sulfide are oxidized into insolubable matter and attach to the surface of the media. Heavy metals such as lead, cadmium, and aluminum are removed from the water by the electrochemical process. They are attracted to the surface of the media, much like a magnet. The media inhibits bacteria growth throughout the entire unit (in fact, has been shown to reduce it up to 90%!), eliminating the need for silver, commonly used in carbon-only filters (silver is considered a pesticide by the EPA and, as such, must be registered with them). Is copper or zinc added to the water in any significant amount? On 2.3 ppm chlorinated water <0.05 mg/l copper and only 0.46 mg/l zinc was measured. The EPA aesthetic levels are 1.0 mg/l for copper and 5.0 mg/l for zinc. And remember that both zinc and copper are essential minerals for good health - the FDA recommends a daily intake of 15 mg of zinc and 2 mg of copper.
STAGE 3 - ADSORPTION: GRANULATED ACTIVATED CARBON
Granulated activated carbon (GAC) is universally recognized and widely used as an effective adsorbent for a wide variety of organic contaminants, such as herbicides, pesticides, industrial chemicals, and trihalomethanes (THM's). Carbon is extremely porous and provides a large surface area for contaminants to collect (the surface area of the carbon in our filter would equal the surface of 50 football fields). Carbon-only filters must also use their capacity for chlorine removal, resulting in a shortened life. They also may use a bituminous coal carbon, which is good at removing chlorine, but not as effective at removing chemicals. We use a high-grade coconut shell carbon that is most effective at removing chemicals. Coconut shell carbon provides a significantly higher volume of micropores than either coal-, wood- or lignite-based carbon. As a result, it is more effective than other carbon types in removing trihalomethanes (THMs) and other chemicals from municipally supplied water. Since our redox media removes the chlorine before it reaches the carbon, the carbon capacity is not wasted for chlorine and is free to concentrate more effectively on organic contaminants.