"So who might do well to buy a Water-to-Go filtration bottle? Students or adults backpacking abroad Commuters; save money and time on buying bottled water Yacht crew who until now would drink tank water with some trepidation or not at all Ramblers worldwide who loath having to buy bottled water when natural springs or fresh water rivers are close at hand Active sportsman training in the wilderness Duke of Edinburgh Award Camping/campers Festival goers, fill up anywhere Each Water-to-Go filter cartridge lasts for 200 litres, or 3 months. Filters are manufactured from a non-woven media that is also called a charged layer membrane. Our filters were developed at the behest of NASA and are constructed utilizing nano technology. Nano alumina along with 33 % carbon and other filtration ingredients are utilized to bring about this amazing new patented process. The nano alumina emits a positive charge when wet and attracts the negative charged contaminants of protozoa, bacteria and virus. This revolutionary new process will make every drop of water more safe and refreshing. Finally a filter that really does what its supposed to do. Unlike carbon block filters that lose as much as 70 percent of their area to the adhesives that hold the block together our carbon has zero adhesives holding it in place. The pore sizes of carbon block based filters are too big to stop any protozoa, bacteria or virus. Yes they filter chlorine and some heavy metals. They basically improve the taste of water without properly filtering out any of the more serious contaminants that can get into water supplies from time to time."