In many poor countries, excess concentrations of fluoride have entered water sources through erosion of sediment and minerals. These toxic concentrations, which are defined by the World Health Organization to be above 1.0mg/L, may result in an array of health complications. Fluoride has been known to induce cell stress, which in turn impairs the function of ameloblasts who are tasked with forming dental enamel. The resulting disease is dental fluorosis, which manifests in the teeth as porous and yellowed enamel. Other potential consequences of exposure to toxic fluoride levels include skeletal fluorosis, which may result in bone deformities, as well as impaired development. Our project involves the development of an operon that will serve as a visual indicator of excess fluoride. We plan to further develop and improve the operon created by last year’s iGEM team, specifically focusing on the fluoride riboswitch and promoter. We are looking for promoters that have an increased gene expression and riboswitches that have increased affinity to fluoride. This would allow for our operon to detect fluoride at levels even lower than 1.0mg/L, a significant improvement from the previous operon.