Everpure claims that its Viru-Pure water filter is the first one in the world that can remove viruses. According to the company, the on-demand filter removes more than 99 percent of all viruses, bacteria, and cysts, along with more common chemical contaminants. It installs and operates just like any other undercounter unit and has a 500-gallon capacity — about a year’s use for most households. The filter costs $550; replacement cartridges are $280. Everpure, 800/323-7873, everpure.com