Our project is focused on developing a biosensor specific for certain water pollutants, with a modular and scalable approach. This approach would make it easy to adapt the response for the detection of different substances. Until now, there have been some experiences of pollutant biosensing in iGEM, but most of them rely on expensive and specific equipment, or qualified people to interpret the results. Being aware that most of the populations affected by consumption of contaminated groundwater don’t have scientific or technical training, we intend the device to be cheap and easily distributed. We also have designed it in a way that any user with minimal training (using an image-based instructions) could easily determine the presence and level of the contaminant on consumption water. The project will focus on measuring a primary pollutant: arsenic. However, its modular and scalable design provides an easy way to measure various contaminants such as nitrate/nitrite, lead, hydrocarbons, etcetera. At the end of this project we expect to have a prototype of the device and a diagram for the system of distribution, collection and centralization of data.