Filter Purifier Part 2 | Waternet
Other Concerns for the Use of GAC
The major problem associated with carbon in any form is bacterial contamination. Wet activated carbon, richly infused with trapped organic matter, provides an ideal breeding ground for bacteria. High bacterial levels are most likely when the carbon is fully saturated and then left to stand for periods of time in between uses. As the water temperature inside the carbon cartridge rises, so does the amount of bacteria. Silver impregnated GAC has a better chance of reducing the amount of bacterial regrowth that occurs but caution must be used, as even the silver can be overcome by the rate of growth of the bacteria.
GAC cartridges that claim they can unload their contaminants by simply backwashing the carbon need to be looked at carefully. Simply reversing the flow of the water does not necessarily ensure cleaning. Backwashing must be done with hot water, at least 145 degrees F. to be effective in stripping the carbon of its contamination. If your water is not that hot, as most hot water heaters are set for 130 degrees or less, backwashing might not do any good at all!
Any GAC filter device that does not restrict the flow of water by using smaller or narrower tubing, such as 1/4 inch pressure tubing connected to the existing plumbing, will not perform as well as those which do have a smaller pressure tube. This generally keeps the water flow rate at between one to two gallons per minute. Any faster flow rate than this and the GAC in any form can not physically absorb the contaminants from the water to be effective at all.
Bells don't 'ring' and lights don't 'flash' when its time to change the GAC filter cartridge in most water treatment devices. Most manufacturers don't provide much guidance either.
They generally say it's time for a change if the bad tastes and odours return or if the water flow is severely reduced because the sediment has clogged the filter. At this point, it is already too late. For example, a carbon cartridge may be able to control the large molecules that add tastes and odours long after the carbon has lost its ability to remove the organic molecules, such as chloroforms (THM'S), from the water, in some cases, the carbon filter may lose its chemical-removing abilities long before the water flow became reduced.
Also a carbon cartridge can be loaded with bacteria and never show any signs of restricted flow rate. About 50% of the manufacturers of carbon filter devices suggest lifetimes in terms of months or even years and in fact should instead be stating the number of gallons of water that can be treated.
A GAC filter cartridge should be considered exhausted or in need of replacement when it can no longer remove at least 50% of the organic contaminants from the water.
SILVER - Nature's Purifier
The value of silver in medicine and as a purifier has been acknowledged for centuries. Egyptians implanted silver plates into skulls with surgery. In Ancient Greece and Rome, people used silver containers to keep liquids fresh.
When settlers moved across the American West, they would purify a container of water by putting a silver dollar in
it overnight and silver dollars were used to keep milk from spoiling.
Scores of independent tests by many methods in six countries have shown that silver promptly kills bacteria in water and maintains water purity over long periods of time. Russian scientists working on water recycling and purification problems for the Soviet space programme have decided on silver as the best long term sanitising agent. Researching the problems of water shortage over periods of several months, as well as purification for immediate use, they determined that ionised silver provides the safest and longest lasting method of transforming polluted waste into potable water.
The impact of silver technology continues to grow. To guard against water borne diseases such as dysentery, more than half the world's airlines now use silver water filters. In Swiss ski resorts, German breweries, American soft drink bottling companies, British ships and a host of other enterprises in seventy countries, silver is used to purify water, according to a report Dr Fred Zobrish presented to a Silver Institute Board of Directors meeting in Washington D.C.
in 1978. The Shell Oil Company has been equipping its tankers with electrolytic silver water purifiers since 1960.
Several other shipping lines, including the P & 0 Steam Navigation Company Ltd, prescribe silver purifiers for the water supply aboard their carriers. More than 100 ships have been equipped - with silver water purifiers which have guarded the health of crews and passengers for years.
The Swiss government has approved silver water filters. They are used in homes and offices throughout the country. Breweries and soft drink bottling companies must start their manufacturing operations with water that is entirely free of odour and taste, that is sparkling clear and germ free. The best way to get water like that, many Europeans believe, is by silver filtration.
These and many other examples of the expanding use of silver in water purification were documented by Dr Fred Zobrist in his address to members of the Silver institute in Washington DC.