Neonicotinoid insecticides are the most widely used insecticides in the world. In the environment, they can be transformed into metabolites that are more mammalian toxic than the parent compounds. My research models the extent these insecticides can be removed from drinking water by granular activated carbon (GAC). I also assess the extent biofilms on GAC transform these insecticides into more, and/or less, toxic metabolites; further elucidating the fate of these compounds in drinking water.