Our primary target is to develop a low-cost sensor to monitor water contamination. In the past, we have developed a Mobile Water Kit to monitor pathogen contamination in potable water [40] and [41]. The great affinity and selectivity of silyl ethers towards fluoride has inspired us in designing and synthesizing a novel coumarin based fluorogenic compound - 7-O-tert-butyldiphenylsilyl-4-methyl coumarin (TBDPSC) compatible with aqueous solutions. Moreover, the compound has been synthesized to attain great specificity towards fluoride and primarily targeted towards rapid, low-cost and portable water testing. This new development will allow us to increase the versatility of MWK towards detecting toxic contaminants in water. A detailed description of the synthesis and characterization of the compound, testing with sodium fluoride (NaF) and interference testing from other anions has been presented. The selectivity and specificity of the compound towards fluoride has been investigated in water and the potential applications of the compound for fluoride sensing in the environmental monitoring have been described.