Fungi are known to occur ubiquitously in the environment. In the past years, the occurrence of filamentous fungi in the aquatic environment has been a subject of growing interest. This study describes the occurrence of various fungal genera in different drinking water sources being Penicillium and Trichoderma the most representative ones (30% and 17%, respectively). Also, 24 fungal species that have not been previously described in the aquatic environment are reported in this study, being once again the major species from the Penicillium genera. This study therefore contributes to the knowledge on the richness of fungi diversity in water. 68% of the described species were found to be able to grow at 30 degrees C but only Aspergillus furnigatus, Aspergillus viridinutans and Cunningharnella bertholletiae were able to grow at the higher temperature tested (42 degrees C). 66% of the species that were able to grow at 30 degrees C have spore sizes below 5 mu m which enables them to cause breathing infections. These were therefore identified as potential pathogenic species. (C) 2013 Elsevier Ltd. All rights reserved.