An opto-electronic tongue, prepared using porphyrins, pH indicators, and their mixtures, has been tested for the analysis of toxic compounds in potable water. The color changes of sensitive dyes immersed in a water solution containing the target analytes were measured with an optical platform made by four LEDs (as light sources) and a digital camera (detector). We demonstrate that blends of dyes might be endowed with sensing properties wider than those of the single constituents, enabling the identification of a range of toxic compounds at concentrations smaller than 10(-6) mol/L. Furthermore, the use of the reporters in a sensor array configuration allows for the identification of the compounds disregarding their concentration. (C) Published by Elsevier Ltd.