Silver Filters

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“Silver Filters” or filters containing silver as an antibacterial agent are very common and deserve special mention. The silver ion, Ag+, has a long history in water treatment, going back to Roman times, and there is no doubt that it can be an effective agent against many bacterial pathogens if the concentration and contact time are sufficient. However, illegal in the U.S. to make that claim, because it is not effective against all pathogens. Many bacteria are relatively immune to silver, and it has no effect on viruses or cysts at all, so antimicrobial claims can easily be dangerously misinterpreted. Thus, such products are allowed to claim only that the silver is bacteriostatic, meaning that rapid, uncontrolled bacterial growth inside the filter is inhibited. Further, it is illegal to suggest that silver has any effect on harmful or pathogenic bacteria; a manufacturer may claim only that silver inhibits the growth of those harmless bacteria that might produce bad taste and odor or premature clogging of filters. Unfortunately, silver ion is not very effective against many of those bacteria, so we are in the ridiculous situation of being unable to make an accurate and truthful claim because it could be misinterpreted and unwilling to make the only permitted claim because it is not very accurate. Everpure, Inc. now promotes the use of its filters with silver in applications where they would be most useful (where they are required by law in other countries, or where bacterial pathogens might be present and users need all the help they can get), while using labeling language that complies with U.S. law.