Although there are many laboratory experiments available to illustrate spectrophotometric or fluorometric methods, few of them introduce the use of luminometry to students. Bioluminiscence, a subtype of chemiluminescence, is produced when an enzyme-catalyzed chemical reaction gives rise to a light emission. Despite the advantages of bioluminescent methods, including sensitivity and specificity, and their increasing use in experimental sciences and biomedical laboratories, their presence in our classrooms are almost inexistent. The luciferase-catalyzed enzymatic reaction has generated a myriad of practical applications, including those derived from the measurement of the ATP consumed in the reaction. In particular, the measurement of the ATP levels in drinking or stored waters directly correlates with their bacteria content, facilitating the development of rapid methods for detecting bacterial contamination. They avoid the long waiting time associated with the traditional microbiological methods, based on the growth of the microorganisms in a suitable culture medium.Throughout the last two years, we have implemented at the University of Malaga a new laboratory experiment for undergraduate chemistry and biochemistry students. In this experiment, students detected bacterial contamination in water by quantifying ATP with the luciferase catalyzed reaction.The experiment was implemented in two different formats, either as a full project developed by students throughout the entire duration of the academic course, or as a shorter version that could be carried out in a single laboratory session. Its application to our classrooms has been very satisfactory, as evidenced by the good academic performance and positive students' perception.