Unfortunately, only filter cartridges containing activated charcoal will remove food coloring from water. The charcoal is only there to remove odors and minor large-molecule organic contaminates, not disease organisms. A filter can work perfectly in removing bacteria and protozoa (but not viruses) and still not remove color from water. The molecules that provide color to water, such as chlorophyll, humic and fulvic acids and dead coyote juice are too small to be removed by a filter. They will, however, be adsorbed by activated charcoal - up to a point.

So, I would not reject a filter cartridge that allowed food coloring through unless it contained activated charcoal. In fact, most filters could be made a bit lighter if the charcoal were omitted. I suspect that it is there more for the tender sensitivities of us civilized types than to provide safe water. Actually, green or tea-colored smelly water is good for you; it has vitamins and minerals in it. <img src="/forums/images/graemlins/tongue.gif" alt="" />