The Shaw Group View Institution's Website 1 article published in JoVE Immunology and Infection A Modified EPA Method 1623 that Uses Tangential Flow Hollow-fiber Ultrafiltration and Heat Dissociation Steps to Detect Waterborne Cryptosporidium and Giardia spp. Eric R. Rhodes1, Leah Fohl Villegas2, Nancy J. Shaw2, Carrie Miller3, Eric N. Villegas1 1National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, 2Shaw Environmental & Infrastructure, 3Office of Ground Water and Drinking Water, US Environmental Protection Agency This protocol describes the use of a tangential flow hollow-fiber ultrafiltration sample concentration system and a heat dissociation as alternative steps for the detection of waterborne Cryptosporidium and Giardia species using EPA Method 1623.