The microbiological quality of municipal drinking water is currently determined by the presence of thermotolerant coliform bacteria as indicators of faecal contamination. This is the first report of a study of microfungi in such waters from Australia. Overseas data suggest that microfungi are responsible for 'off-tastes ' and some are recognised as opportunistic human pathogens.The primary aim of this seminal study was to determine the qualitative and quantitative microfungal (filamentous and yeast/yeast-like) loads in waters from the reticulated water supply system in a tropical Australian city which abstracts untreated water from a river impoundment prior to classical treatment procedures. amples were regularly obtained from both stand-pipes (9) and storage tanks (6) throughout the city over a period of ca. 1 year and microfungi were recovered by Millipore™ filtration (0.45 Ilm). Filters were incubated for at least 3 days on malt extract agar with chloramphenicol for the suppression of bacterial growth. Colonies were counted and then identified microscopically. Numerous physicochemical parameters of each sample were recorded using a YSI multiparameter meter. Microfungi were rarely recovered immediately post-chlorination at the treatment plant. In contrast, microfungi were almost always recovered, sometimes in very high numbers,from all stand-pipes and all storage tanks tested. In total 61 genera were identified along with a large number of non-sporulating isolates. The genera most frequently recovered were Cladosporium (51.9%), Penicillium (17.4%), Aspergillus (6.6%), Fusarium (2.9%) and Pithomyces (2.8%).