Using Lambda bacteriophage tails, the WLC-Milwaukee iGEM team plans to develop a novel way to detect Escherichia coli in water samples. Lambda phage is an extremely well studied and highly specific bacteriophage that binds to LamB, an outer membrane protein in E. coli. For our detection method we use the J protein that resides in the tail region, which is a necessary component for LamB recognition. Our “Phage Gauge” will involve a purified phage tail solution conjugated to an enzyme that will act as a color indicator. The phage tail will bind to LamB in E. coli cells, and allow detection of E. coli at low concentrations. With a range of color brightness, our test will be quantitative in nature and provide a solution to the largely qualitative tests on the market. Because the test will yield results in minutes, it can compete with already marketed tests. Our testing method, while currently specific to E. coli could be applied and used to detect other bacterial strains based on the bacteriophage tail protein used.