What is required to be a “purification filter?”
EPA’s definition of purification includes the removal of >99.9% of parasite cysts, >99.99% of viruses and >99.9999% of bacteria. If a filter or system is not certified at these levels, it cannot be considered a “purifier” grade filter. If a filter is only certified to 99.9% of bacteria, tens of thousands of bacteria could pass through the filter in a few ounces of water.