The presence of Escherichia coli (E. coli) is an indicator of fecal contamination in water which is suggestive of the potential presence of pathogens. To reduce the chances of waterborne illness and outbreaks the U.S Environmental Protection Agency (EPA) has mandated a “Maximum Contaminant Level Goal” (MCLG) of zero per 100 mL of sample for total coliforms in drinking water indicating a total absence of E. coli. Bacteriophages (phages) based biosensors are gaining attention and are being engineered to detect the presence of their host E. coli. Phages are viruses that infect only bacteria and are harmless to humans. Phage-based biosensors, engineered to have a reporter gene, bind specifically to their host bacteria via their tail fibers. The addition of an external substrate produces a measurable signal upon interaction with the reporter enzyme indicating the presence of the host bacterium. The current limit of detection of E. coli in drinking water using phage-based biosensors is <10 CFU/100 mL. This study investigates decreasing the limit of detection of E. coli by reducing background signals to undetectable levels. We will accomplish this by silencing the reporter gene in the engineered phage during the initial propagation step. This will reduce the carryover reporter enzyme added to the water samples. Antisense RNA (asRNA) have been designed to target the reporter gene during propagation thus reducing translation. We hypothesize that by silencing the reporter gene during propagation, less enzyme will be introduced into the assay resulting in a lower background and corresponding to a lower limit of detection.