For domestic use, this green Trail Filter for your Water Filtration Cup (Item No. 202481) makes water from virtually any source great tasting and safe. It removes 99.99% of bacteria, including E. Coli., and is effective against odors, flavors, chemicals, toxins and protozoan cysts. An anti-microbial agent inhibits the growth of mold, bacteria, fungus and mildew between uses. This filter can be used about 300 times: it cleans 40 gallons of water (approximately 3 glasses a day for 3 months) and is sufficient for most people in the United States. Includes one filter.