Really doesn't look much different than the Guardian Sweetwater filters. Obviously, the larger units are different and resemble reverse osmosis systems.<br>I think that to decontaminate "city water" all that would be required is a suitable particulate filter, cartridge to remove chemical impurities (after all, nerve agent is a simple chemical contaminant), and an ultraviolet unit that will kill any viruses or bacteria in your water.<br>Just a thought<br><br>Jeffery S. Anderson, M.D.<br><br>