Chlorine dioxide is effective against a broad range of pathogens, including: bacteria, viruses, protozoa, yeasts, fungi and bacterial spores. It is particularly effective against waterborne pathogens, such as: E. coli, Giardia and Cryptosporidium, which are resistant to other disinfectant-types.
For more information, you can research Chlorine Dioxide on the EPA's website without the need for a registration number.