Legionella is a common water-borne bacteria that contaminates drinking water, causing a deadly type of pneumonia called Legionnaires disease. To combat this problem, we are designing a system that can detect legionella in water, using bioluminescence to indicate whether the water is contaminated. Specifically, our system employs the use of the lux operon that will be turned on when it detects legionella in the water.  Once the promoter of the operon is turned on, it will allow the production of luciferin and luciferase, both of which will react and create bioluminescent light.