Although chemicals (e.g., bleach) are sometimes used for disinfecting small volumes of drinking water for household use, chemical disinfection is generally not recommended for commercial establishments because of the lack of onsite equipment for testing chemical residuals. Furthermore, Cryptosporidium is poorly inactivated by chlorine or iodine disinfection. Cryptosporidium can be removed from water by filtering through a reverse osmosis filter, an “absolute one micron” filter, or a filter certified to remove Cryptosporidium under NSF International Standard #53 or #58 for either “cyst removal” or “cyst reduction.” (see A Guide to Water Filters for more information) However, unlike boiling or distilling, filtering as just described will not eliminate other potential disease-causing microorganisms, such as bacteria and viruses.