Water is an essential and indispensable resource for the survival of human beings. The regulation and monitoring are fundamental to make water consumption without the risk of transmitting pathologies. The main measure used to analyze the potability of water is the identification of the presence of coliforms. In rural areas, to guarantee the water supply, artesian wells are normally used. This mean to obtain this resource is not recommended. This is due to the fact that these sources generally do not receive adequate treatment and have the potential to transmit diseases to the population that uses these sources. Thus, the aim of this study is to evaluate the potability of water from artesian wells in rural and urban areas of the city of Guaraci, PR. To evaluate the potability of water sources, we used the Colilert® chromogenic substrate method. From January 2014 to December 2015, 146 samples were collected from artesian wells in rural and urban areas in the region of Guaraci, PR. Among the 146 samples collected, 61 (41.78%) presented total coliforms, in which 23 (15.75%) of these samples presented Escherichia coli. On the other hand, the remaining 85 (58.21%) samples showed satisfactory results. According to the Brazilian Ministry of Health, in relation to the microbiological quality of water, in 100 mL of water for human consumption, total coliforms and E. coli should not be present. In addition, it was possible to observe that among the 146 samples, 82 were not treated and among these, 36 (43.90%) were satisfactory and 46 (56.10%) unsatisfactory, while, of the 64 treated samples, 58 (90 .62%) presented satisfactory results and 6 (9.38%) unsatisfactory, showing the effectiveness and importance of the treatment of these water sources to eliminate bacteria and facilitate consumption for the community The presence of bacteria in analyzed samples denotes the need to treat these sources, reducing the transmissibility of possible pathologies associated with their consumption. Therefore, it is necessary for consumers that this water source is treated following the correct treatment procedures, such as the application of chlorine and the boiling method, in order to reduce the amount of microorganisms in the area.