The Nephros S100 Handheld Shower Filter purifies EPA-quality water and makes it suitable for drinking, surgical handwashing, and medical equipment cleaning. This model type is a point-of-use microfilter capable of retaining bacteria for 90 days and ideal for emergency use. The S100 Handheld Shower Filter is FDA 510(k)-cleared as a Class II medical device. .1 Micron Filtration.