A. Most filters on the market are soft, granular charcoal, which are movable activated carbon filters. These filters do not have a definite pore size and can get holes where bacteria can breed and grow. Multipure’s 0.5 micron (1/50 of a thousandth of an inch) solid carbon block proprietary technology effectively eliminates this problem protecting your health and water supply, providing clean, fresh tasting purified water and peace of mind in every drop!