Through the use of multiple advanced filtration processes, the Extream water purifier kills virtually all water-born bacteria and viruses. The simple, and self-contained system makes the bottle ideal to use on traveling trips whether it's camping in the forest or backpacking around Asia. Filtration is accomplished through a filter cartridge that needs to be replaced after every 160 refills, or 26 gallons of water. Use this in your office instead of plastic water bottles and you should recoup your cost within a year.