Our purifiers use a pentaiodide resin which is a highly concentrated form of iodine. It is a unique purification technology based on the natural process of electrostatic attraction. The resin has a positive charge that attracts negatively charged contaminants in the water. When the contaminant comes into contact with the resin bead, sufficient iodine is released to penetrate the microorganism. By this 'fatal attraction' bacteria, viruses and protozoa are neutralized and killed. This technology was developed by Kansas State University in the early 1970s. Proven to be a highly effective and practical means of purifying water, NASA chose to use the iodinated resin technology in the Space Shuttle program.