Bacteria are considered as the most diverse microorganisms on earth. However, bacterial diversity is unknown in some ecosystems, such as leachate treatment plants. In the present study, we characterized culturable bacteria isolated from six lagoons and one pure leachate to assess whether bacterial morphotypes can be used as biodiversity indicators. The sampling site was a leachate treatment plant located in Santiago de Cali. Overall, 311 bacterial morphotypes were collected from six lagoons, and a pure landfill leachate, and were identified using colony characters. Four biodiversity indexes related to species richness and abundance as well as to the estimation of the number of species present were calculated. The results show a great diversity of bacterial morphotypes in all samples. Further, the highest estimates of biodiversity were observed at lagoon 6 physicochemically treated, and the lowest estimates were observed at lagoons 5 and 8. The leachate generated in the sampled lagoons, which were composed of different elements, allows for the colonization of diverse bacteria. Moreover, these bacteria were resistant to the treatment plant processes, thereby explaining the highest diversity observed at the lagoon 6. Our results showed that bacterial morphotypes can be used as biodiversity indicators in ecosystems.